Adventure and Encounter Structure
1. Thinking outside the box.
I understand, again, general is often important because you want it to apply to the most tables as possible. But generality, and traditional, can really make it bland. So, again, start it fresh. Recreating the wheel is not what I mean, but merely putting a shiny hubcap on it.
Use some of the advice from the DMG2. Start it with a Vignette. Start it with the PCs dieing, and being resurrected. Start it with something interesting.
One of my favorite adventures is "Three Days to Kill", a 3.0 adventure. The premise is really simple: the PCs are hired by one group of bandits to disrupt a meeting between another bandit group and a cult. This meeting would disrupt the balance of the various bandit bands by giving one more power and - it really doesn't matter to the PCs, because it's a simple odd job. The PCs can deal with the situation in any fashion they want, at any time they want, so they are free to formulate their own plan.
I'll touch on that fact later, but simply put it's a different kind of adventure. Not only are the PCs not Fighting The Good Fight, but they're in a gray area and they're doing something small that will possibly have ramifications if they care about it (hey, it addresses cultists and doesn't give these bandits too much power; highwaymen with infernal backing could be much worse).
Paizo does this with the start of each adventure Path, by getting the players to all buy into one concept that's important for most of the whole adventure. "You all are hired to work at a casino" "You all are guards on a caravan" "You all are part of this little community". It does hurt generality, but it makes up for it in unity and tieing the PCs strongly to the plot, as well as strongly to one another, and serves the purpose of being more than "I'm an adventurer and I'm off on an adventure".
Don't be afraid to try something different.
2. Adventure Structure: Think Outside the Dungeon
I know it's called "DUNGEONS and Dragons", but every adventure doesn't need to be "fight your way through double digits worth of rooms to fight the guy at the end".
This goes back to plot, but it's also just related to the adventure structure. Return to Castle Ravenloft did some really good things here: A) It put the PCs in the middle of two villains. They had to decide who to oppose (and thus who to side with), but ALSO, B) the PCs could go about destroying shrines/sites of power. Doing so weakened one of the villains. This was completely outside of the Dungeon, but had relevance to both the plot, and the mechanics.
It gave the players Plot Options. Just like "Three Days to Kill" was very open ended, the players could debate on those choices. The DMG2 talks about offering players meaningful choices, and even something as simple as "Right or left" needs to have some baring on relevance (Right goes into the Volcano of Burning, and Left goes into the Swamp of Despair, but either will get us to the other side).
So an adventure that is built like a flow chart would be much better than an adventure that is "Grind through these rooms til you get to the end."
3. When In the Dungeon, Don't Torture Variety
One of my biggest beefs with WotC's modules is the monster monotony. In KotS, you have:
4 consecutive combats with kobolds
4 consecutive combats with goblins.
3 consecutive combats with hobgoblins.
In Thunderspire Mountain, you had the same thing happening in the Duergar area. Wall To Wall Duergar with little variation. Scepter Tower of Spellguard was no different; constant undead in the lower levels, constant dark creepers/spiders in the upper levels.
If I'm going to fight the same type of enemy multiple times, each encounter better be different. The biggest sin (imo) was that in KotS, encounter 1 and 2 are not different![/b]. The only difference is that the 2nd has kobold skirmishers. They are on the same map for Thor's sake!
More importantly, instead of fighting the same monsters consecutively, at least toss in different encounters between them. The Interludes were a good attempt, but PCs jumped by kobolds (twice) weren't going to pull away and go to the Camp site. I also had a hard time giving PCs a reason to go back to town for the second interlude - they wanted to stay in the dungeon and slog through it, resting just outside/in cleared areas instead of returning for any reason. So back up your interludes with incentives to have them.
Pyramid of Shadows and the Well of Demons in Thunderspire Labyrinth are great examples of mixing up monsters/encounters. Now, Pyramid of Shadows has its issues (I'll get to later), but man, every room (except for the plant guys) is different! Vastly different! It's got variety in spades, I'll give it that! I also absolutely adore H2's the Well of Demons. Every room, while thematically, and plot-wise, are linked, each room is vastly different and offers different issues. It's a great thing, that you could rip out and drop into any adventure as a cool and intriguing site. Trollhaunt was also awesome here - sure, you fought those damn trolls many times, but they were paired different things each time.
I love monsters. And I love using them. So the monotony issue is big for me. I had to go back and re-populate those encounters with non-goblin, non-kobold, non-hobgoblin helper monsters (drakes, giant bugs, traps etc) just each encounter stood out from "just another fight with goblins".
4. Dungeons Shouldn't Torture Players
This goes back a little to point 3, but simply put, the dungeons in the majority of the modules are too long. Pyramid of Shadows locked people in a dungeon for 3 levels! Even if it's variety, the PCs just can't roam, can't go get a beer at a tavern, buy/sell equpment, can't do anything but move forwards!. Scepter Tower of Spellguard was nothing but a dungeon crawl. Same with P3. The players should not feel like the seasons changed between going in and coming out of teh dungeon, because they have spent so many sessions in there. This is I believe the biggest sin of the SoW aside from plot linkage (see next post).
This is one thing that made the non-Duergar areas of H2 very enjoyable. They were, if nothing else, short.
My personal rule of thumb is that a dungeon's welcome has been overstayed after the 6th encounter.
On the topic of monotony and encounters, I loved Trollhaunt. The various random encounter suggestions, the encounter ideas for exploring the Feywild, I loved those. They were rife for ideas for other products, and again, let you inject it to break up the monotony. It also let you address the issue if your players would prefer to explore, rather than battle.
I understand that in a module, you are trying to level the PCs up so the encounters later are balanced for the levelled up PCs. Thus, the more encounters they skip, the worse they are. Sure. But, break those encounters up in terms of location, in terms of pacing and in-game time, break them up with other things to do like social encounters and skill challenges.
5. Encounter Structure
Just as I don't want to fight the same monsters consecutively, I also don't want to fight in the same room multiple times. KotS tried to vary it up in the first level of the Keep, but really, there's not a lot of difference from room to room; a little difficult terrain here, maybe a platform there, but not exciting. Use all that fantastic terrain you publish. Put the encounters in exciting locations - logs on a river, a decaying bridge that will fall apart soon, a battle on a tower that's on fire/crumbling beneath you. Paizo had a battle in a tower that was rolling down a cliff into the ocean - it's hard to not sit back and go "Wow". Not to mention the DMG2 and the many fiddly bits - terrain powers, or other interactive material (Mike Mearls posted how he'd improve the Dragon encounter in Kobold Hall; this is an example of interactive terrain/hazards that make a simple slugfest more remarkable).
Beyond the trappings of the area, I again point to DMG2. Use those Encounters as Story, and more importantly, the Encounter Objectives. Objective encounters are great, and I want to see examples of them, I want to see them integrated into the story, I want to see them work good. I love them so hard, but I never see them.
If I don't sit back after an encounter and go "That was different from the lsat two I just had", then I think it's a wasted encounter, in terms of excitement and variability.
6. Mixing It Up
In Trollhaunt, mid-way through going through the Warrens, the PCs encounter a dragon that's willing to parlay. This is great. It's someone to talk to, to get information from, and to possibly NOT FIGHT. KotS tried this with Sir Keegan, but I felt it fell flat.
Compare this to Pyramid of Shadows. Every Single Guy in there, even if they weren't trying to eat your face, were going to just stab you in the back. There were no friendly NPCs, no "take a breather" zone. I believe very firmly that Pyramid of Shadows would have been much better off had the Pyramid had a shopkeeper in there somewhere, or a bar.
Now, some adventures in Dungeon do mix it up, they toss in skill challenges left and right. But I haven't seen those in the Published adventures.