Amen on that last point in particular! You never know exactly what a player will find fascinating that is a total throw-away section to you. If they love it, spend time on it.

In my most recent session the party had just finished a quest and was getting ready to leave civilization for a while. I pointed out that they probably wouldn't have the chance to do any shopping in the near future, so they decided to go shopping. And somehow, this became a really involved excursion - tracking down the proper merchant, trying to convince the merchant to pay top dollar for the PCs' gear because of the stories associated with it, and so on. So we shopped for a while! It was unexpected, but lots of fun.

The last two points are very important and something that new DMs sometimes struggle with. "But I works for days on this entire story arc, and they ignored it completely! Instead, they're more interested in the fish population! Ugh!"

Yeah, it happens. Just roll with it. : > I tend to encourage and expand on anything the players have an interest in. If they're interested and engaged in the topic - even if I'm not particularly thrilled - it's better than having a table full of bored players and a DM desperately trying to cling to a story nobody wants to follow. Plus, if the players learn that they can trust you to take their characters' interests seriously, they will start to hand you story arcs on a silver platter.

It really works both ways. In order to have a decent session, players need to buy in to your story to a degree, and unless you're running a straight splat game, you need to buy into your players' stories as well. It's a two-way street.

Lingo is effective and fun. You're right about not overdoing it, though. Too much of it and the players will get that glazed look in their eyes.... Not good. Or, worse, they'll think, "Gosh, you are trying way too hard..."

I wish I could do good voices. I have played with some people who do a fantastic job, but alas, I either sound like myself, or... Um. Myself, with a bad cold. Or drunk. But that's usually because I am.

Some other quick random tips:

Not every game has to be an epic event. Taking a session or two to run a "Ship of Fools" for some comedic value can be a nice break from the norm.

Set aside 5-10 minutes after your session for feedback. Running a game is far more Art then Science, and the only way you can fix your mistakes is to know about them in the first place. Some honest feedback will make you a better DM and everyone will have more fun.

Be flexible where you can. If you have a player that really wants to play a hermaphrodite gnoll monk raised by gnomes, see if you can view the idea as an opportunity instead of just a player on drugs. If there's an aspect or two that just won't work for whatever reason, see if the player would be willing to make a few small changes. They are almost always glad to do so.

Reward creativity. Giving circumstance bonuses to rolls or a small XP bonus is a nice way to give the player a tangible reward for being clever and it encourages this kind of play.

Never be afraid to say, "This is my game, so if griffins are an intelligent race devoted to a sun god and their temples are places of learning and rest, then guess what? I don't care if the Monster's Manual gives them an Intelligence of 6. My griffins aren't those griffins."

If you have a player that, in combat, outshines the rest and tends to make fights a bore for everyone else, find ways to craft the encounters so that everyone can be involved and play an important role. Try separating the one player from the rest, employ environmental hazards, multiple points of attack, an encounter where simple damage won't win the day, etc.

Conversely, if one character is severely lacking compared to the rest to the point where she isn't having fun, see if you can work something out. Perhaps an item with a good bonus, or allow the character to change some feats/spells, or assist with tactics.

The point is to have fun. If fudging things a bit makes things more fun, then by all means do so.

Also: Weird, Blogger's OpenID integration is broken for me. I'm a sad griffin.