Things I've Learned on The Other Side

Playing for quite a few months without DM'ing can be very interesting, especially if you have a good DM and little experience as player. Although we are playing some Pathfinder, I think I have a couple of personal annotations I should write somewhere, at least to have them more clear in my own mind.

• It's pretty difficult to come up with an encounter where every single class (or, at least most classes) can be challenged. Still, it's very important! I found that when I think about a room, I'm often focused on the common classes (Clerics, Magic-users, Thieves and Fighters), and this is wrong. Players who have had the chance (or decided, in the case of post 3.0 games) to play some unusual classes (Rangers, Barbarians and such), are very excited about their special abilities when they roll up their characters. For that reason, if they never get the opportunity of using their special abilities, they grow bored pretty quickly.
• Despite the fact I've always thought there were too mnay monsters in D&D, I know now that it makes a lot of sense! If you face goblins, and then goblins, and goblins again, the warriors might be happy, but other characters may not. The Magic-user who has to thrown his magic missile(s) again and again and again until he runs out of spells, for example. The key is using many different monsters, possibly many different monsters in the same encounter.
• I've always wrote adventures where the difficulty of figuring out exactly what was going on was a bit hard, and the party had to fight its way never having a definite idea of the situation. Now, I know that players need clear targets: take that back, rescue that girl, slaughter that sorcerer. The frame may still be obscure (note: obscurity is not total darkness), but the single "quests" should not, no matter if they're imposed by the plot or freely chosen by the party in a sandbox style game.
• Unsurprisingly, rolling on the table in front of the players is the best thing a DM can do.
• Never be unprepared. You can think that your improvising skills are pretty strong, but players have a sort of natural sixth sense for such things. Spend a night or two seeing someone else DMing, and you will notice this too. It's important that everything looks planned, no matter how random it really is. I'm not saying that no one should DM by total fiat – I'm saying that if I smell total fiat when I play a character, I kinda lose interest. The reverse is also true: don't make planned things seems random, 'cause it's even worse (especially when they ruin some of the party's plans.)
• Make combat move fast, especially for those who don't have 45 different things to choose from each round. Pathfinder is particularly bad on this point, especially if you have several fighters in the party (who attack using 4 talents every time, and have to choose the ones to use from round to round, and take about ten minutes figuring out all their bonuses to hit/to damage), and one magician, who only casts magic missile and then has to wait ten minutes for his/her turn to come again. Although I don't like miniatures that much lately, they definitely speed up the game.
• Let combat be interesting! If in Pathfinder fighters can be a pain in the neck if you're not one, in previous editions they're boring as hell. "I hit it", "I hit it", "guess what? I hit it". Never be too mean with modifiers, just let them do something different with reasonable chances of success from time to time (disarming, landing, breaking through and so on.)
• USE. THE. FUCKING. MORALE. For Demogorgon's sake.

I'm quite sure I've forgotten something, but I don't mind too much. These are all quite good points, and I think they're more than enough for my future design plans.