The, as of this writing, still ongoing 'Save my Game' thread, brought up several basic DMing mistakes that crop up a lot. As I sat here I thought about a few more, not wanting to clog the thread I started a new one.
#1, Obvious clues? One I've run into time and time again. DM leaves clues to what's going on about to happen, defeat the bad guy ect. And thinks they're totally obvious. No one else sees them, because surprise they aren't obvious to anyone else. Even worse is when they are pointed out they still don't see them as leading to the conclusion the DM was leading to. Put them up here if you have to, but get a second opinion on how good the clues are.
#2 Monty Haul, DM doesn't plan out the money rewards well leading to charaters with obscene amounts of money. I was guilty of this one, the rewards were based on the characters keeping a small fortress they cleared out and one of them held title for. I gave them larger rewards based on the upkeep and taxes on a remote outpost. When they gave the Keep away I had to throw away my planned rewards as being to much and use the DMG tables, which were almost as bad. (The updated tables in MIC are far better at balanced rewards.)
#3 If your monster/villian/ect has magic items they can use, use them!!! Even if you randomly roll treasure for a critter, if it has ssomething it can use go back and make a tactics note they have it and use it. In that same line of thinking pre-buff your encounters. If you have a standard Orc ambush (5-8 orcs+1 orc adept) put some basic useful buff spells or scrolls on the adept and use them, at this low level encounter Bless can make all the differance.
#4 Tactics. With some exceptions, most monsters aren't going to charge straight at the party and fight toe to toe. This has not stopped DMs from having every monster do just that. Hobgoblins misuse has always been a pet peeve of mine (and of several writers of Dragon as well as over the last several decades I know of at least 3 articles that complain about it) They tend to get treated as variant orcs. Many DM's miss this line
This line is basically unchanged from my first edition books. Yet I keep seeing them charge forward and fight to the death just like orcs. These creatures are born with one purpose, to wage war. Considering they lack the strength advantage of orcs, or the mass numbers of goblins they have to be skilled. Read up on ancient cultures war tactics, romans or spartans are good choices. (I prefer roman legions over the spartans.)
#4 This is table top not Baldurs Gate
ark Alliance, not every encounter is combat, reward your players for talking their way out of trouble, give exp for completing social goals, especially unspoken ones.
#5 Pay attention to the character traits your players bring to the game. Many people play characters far differant from themselves, if they've established certain character traits, don't be surprised if they keep in character around NPC's even if they are intended plot hooks. Example: Playing in a D20 modren game our GM was rather surprised when 2 of us just up and left a meeting with a major NPC, because we objected to his tampering with our minds. Yet this was completely in character for us as we both had in character reasons for dislikeing anyone messing with our heads. As a result the game broke down since we needed to know what he was going to say. We managed, eventually to get back on track.
#6 Don't always give into players on side issues. I've been in at least three games that collapsed under the weight of 'on the side' things we were doing that came back to haunt the GM, and in one case almost came back to de-soul a player (bad deal with Asmodeus). Pay attention to what these seemingly unimportant items are.
#7 I'll say it again, be prepared, the absolute worst game I was ever in the DM frequently showed up and just randomly rolled what monster we were going to fight, repeatedly, all night long.
#8 If you think the players are pulling a fast one make them back up and step by step them. If your not sure, look it up, if its vague go with your gut. Your not BA and their not Brian.
#9 It is not DM vs Player, Don't fall into this trap.
#10 avoid absurd McGuffins, I think the worst one was a sword that contained the soul of every kind of dragon, made the weilder completely immune to thier magic/breath weapon and could kill dragons in single hits, recieved at level 3, the dragon ginsu killed about 26 dragons in not to many adventures later. Might as well have called it the sword of power-leveling.
#11 If your going to house rule work it out in the begining and stick with it. Nothing annoyed me like the DM who after we found about 20 items arbritrarily changed how Identify works.
Became 'The spell determines one magic property of a single magic item, and casting time became 6 hours.
#12 Don't lie to railroad your players, especially about map features. In a Conan game (which after the first game I never returned to) the GM in an attempt to keep our enslaved selves from escaping (thus 'ruining' his game plan) he declared the city (Shadazar) was in a desert with no water in 5 days travel in any direction, this seemed rather strange to thoose of us looking at the maps, especially since Zamora has a rather large population, and what little desert there is in Zamora is 60 miles across (slightly less than 3 days travel) and that's taking the long way. We didn't argue just to keep th adventure moving, me might as well have, the whole adventure was lame and pointless.
That's all I can think of at the moment, mostly from getting frustrated at the memories. Three of these examples are a single DM who ran for almost 2 years. (it was a game strore he booked the time slot, he got it until he stopped coming or we did.)
#1, Obvious clues? One I've run into time and time again. DM leaves clues to what's going on about to happen, defeat the bad guy ect. And thinks they're totally obvious. No one else sees them, because surprise they aren't obvious to anyone else. Even worse is when they are pointed out they still don't see them as leading to the conclusion the DM was leading to. Put them up here if you have to, but get a second opinion on how good the clues are.
#2 Monty Haul, DM doesn't plan out the money rewards well leading to charaters with obscene amounts of money. I was guilty of this one, the rewards were based on the characters keeping a small fortress they cleared out and one of them held title for. I gave them larger rewards based on the upkeep and taxes on a remote outpost. When they gave the Keep away I had to throw away my planned rewards as being to much and use the DMG tables, which were almost as bad. (The updated tables in MIC are far better at balanced rewards.)
#3 If your monster/villian/ect has magic items they can use, use them!!! Even if you randomly roll treasure for a critter, if it has ssomething it can use go back and make a tactics note they have it and use it. In that same line of thinking pre-buff your encounters. If you have a standard Orc ambush (5-8 orcs+1 orc adept) put some basic useful buff spells or scrolls on the adept and use them, at this low level encounter Bless can make all the differance.
#4 Tactics. With some exceptions, most monsters aren't going to charge straight at the party and fight toe to toe. This has not stopped DMs from having every monster do just that. Hobgoblins misuse has always been a pet peeve of mine (and of several writers of Dragon as well as over the last several decades I know of at least 3 articles that complain about it) They tend to get treated as variant orcs. Many DM's miss this line
SRD said:These creatures have a strong grasp of strategy and tactics and are capable of carrying out sophisticated battle plans. Under the leadership of a skilled strategist or tactician, their discipline can prove a deciding factor.
This line is basically unchanged from my first edition books. Yet I keep seeing them charge forward and fight to the death just like orcs. These creatures are born with one purpose, to wage war. Considering they lack the strength advantage of orcs, or the mass numbers of goblins they have to be skilled. Read up on ancient cultures war tactics, romans or spartans are good choices. (I prefer roman legions over the spartans.)
#4 This is table top not Baldurs Gate

#5 Pay attention to the character traits your players bring to the game. Many people play characters far differant from themselves, if they've established certain character traits, don't be surprised if they keep in character around NPC's even if they are intended plot hooks. Example: Playing in a D20 modren game our GM was rather surprised when 2 of us just up and left a meeting with a major NPC, because we objected to his tampering with our minds. Yet this was completely in character for us as we both had in character reasons for dislikeing anyone messing with our heads. As a result the game broke down since we needed to know what he was going to say. We managed, eventually to get back on track.
#6 Don't always give into players on side issues. I've been in at least three games that collapsed under the weight of 'on the side' things we were doing that came back to haunt the GM, and in one case almost came back to de-soul a player (bad deal with Asmodeus). Pay attention to what these seemingly unimportant items are.
#7 I'll say it again, be prepared, the absolute worst game I was ever in the DM frequently showed up and just randomly rolled what monster we were going to fight, repeatedly, all night long.
#8 If you think the players are pulling a fast one make them back up and step by step them. If your not sure, look it up, if its vague go with your gut. Your not BA and their not Brian.
#9 It is not DM vs Player, Don't fall into this trap.
#10 avoid absurd McGuffins, I think the worst one was a sword that contained the soul of every kind of dragon, made the weilder completely immune to thier magic/breath weapon and could kill dragons in single hits, recieved at level 3, the dragon ginsu killed about 26 dragons in not to many adventures later. Might as well have called it the sword of power-leveling.
#11 If your going to house rule work it out in the begining and stick with it. Nothing annoyed me like the DM who after we found about 20 items arbritrarily changed how Identify works.
SRD said:The spell determines all magic properties of a single magic item, including how to activate those functions (if appropriate), and how many charges are left (if any).
Became 'The spell determines one magic property of a single magic item, and casting time became 6 hours.
#12 Don't lie to railroad your players, especially about map features. In a Conan game (which after the first game I never returned to) the GM in an attempt to keep our enslaved selves from escaping (thus 'ruining' his game plan) he declared the city (Shadazar) was in a desert with no water in 5 days travel in any direction, this seemed rather strange to thoose of us looking at the maps, especially since Zamora has a rather large population, and what little desert there is in Zamora is 60 miles across (slightly less than 3 days travel) and that's taking the long way. We didn't argue just to keep th adventure moving, me might as well have, the whole adventure was lame and pointless.
That's all I can think of at the moment, mostly from getting frustrated at the memories. Three of these examples are a single DM who ran for almost 2 years. (it was a game strore he booked the time slot, he got it until he stopped coming or we did.)