randomling said:
Does anybody have a magic potion of confidence,
Anger. Failing that, alcohol.
Not sure if I'd seriously recommend either, though.
randomling said:
or failing that, some tips on how to bolster my self esteem,
I assume the people you are gaming with are friends, or at least friendly acquaintances?
You don't have anything to prove to them, don't worry.

And even if you aren't satisfied with your work, you'll at the very least have learned something that will make it easier next time.
randomling said:
look slick when I'm not sure where to go next,
A few things:
Preparation. Make sure you have a few aces up your sleeve before starting the session. Then pull them out when needed.
That is, create some NPCs, monsters, locations, etc. that might come in handy later. Both general ones (guards, taverns, raiders) and well-detailed specific ones relevant to the campaign (and possibly even plot at hand) are handy to have.
When plotting, don't place plot-relevant things - even minor ones - in a vaccum in your mind. If you know not only what a group of NPCs is going to do, but also
why they are going to do it, you can tell more easily how they'll adapt to specific situations, to what lengths they'll go to achieve the goal, what they are willing to risk, and so on. The same goes for NPCs' knowledge - always know what your NPCs know, so you can have them act accordingly and can instantly decide what information PCs can gain by interrogating them.
This goes for the big picture as well. If the PCs manage to completely thwart a nefarious scheme that you thought they could only unravel in part, knowing the personality, motivations and knowledge of the mastermind behind it makes it easier to decide on his next step.
That said, when it'd be more useful, feel free to change anything that hasn't been presented to the PCs yet, even if it's just sitting right behind the next corner.
'More useful', in this context, doesn't mean you should punish PCs for being creative, nor bail them out of any mess they get themselves into. Rather, it means that if something helps keep the game moving (or interesting) but didn't occur to you previously, feel free to use it if you think it's better than your old plan. Often such changes are prompted by PC actions, of course.
Also, when making such changes on the fly, knowing the big picture well (see above) makes it easier to figure out the ramifications (if any) of the change.
If you have no idea, nor anything to fall back on, you obviously need to make stuff up, which isn't always easy. So it's generally in your interest to keep it simple.
If you can pull it off, shamelessly rip off some movie, novel or other story. But try to pick one of a different genre and preferably one that's not too well-known among your group. Unlikely candidates are often more useful than too obvious ones; I could run games for months if not years drawing on little else besides Yu-Gi-Oh (especially if my players are not
too familiar with it).
Of course, making some creative changes goes a long way to making a story your own.
Anyway - again, when improvising, keep it simple. Unless you can pull off something truly outlandish, that is, though this sort of inspiration can't usually be counted on to suddenly appear when it's needed.
Lastly, if all else fails, call for a short break to think things through.
randomling said:
or outwit players with law degrees and PhDs?
Make it easy for them to inadvertantly act on incomplete or false facts; also, get them to act on emotion rather than logic. (Especially overconfidence. Pride goeth before the fall and all that. Fear, when available, is good too. Greed can work sometimes, especially when someone offers them magic items for a low, low price - or, and often more effectively, offers to power up existing items if they hand them over for a few days.)
E.g.:
Have NPCs give them fake evidence (intentionally or not).
Play to their self-confidence by making things easy at first. Throw them some tricks that are easy to look through. (That is, have the enemy do it, of course.) Make them overconfident enough to become incautious.
Use illusions or at least disguises. Make the strong seem weak (an ogre that's looking like a devourer or iron golem) and vice versa (a bunch of demons and their orc lackeys - except that one of the orcs is actually an even more powerful demon using magic to look like an orc). Make them waste spells and ammunition on things that aren't really there (mirror images or other illusions) or not what they appear (a spellcaster attacking from behind a tree that, thanks to illusion magic, is looking like a spellcasting devil).
Don't overdo it, though; you don't want your PCs to become so cautious that they pause every 5 minutes to check for illusions, etc.
Create situations that all require different approaches for the best chance of success; don't let them get away with using the same tactics over and over.
Heh. But don't forget to reward your players and don't
constantly trick them. Instead, use the above and other tactics to create situations that are deliberately designed to be nasty tricks yet
relatively fair and easy to win. This makes your players feel less hosed and is only fair if you put them through all this. (Also, the more they trust you, the easier it is to trick them later.

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