I find that in a game, there are 3 main types of players. The first are promising people who are new to the game. They are interested in it, and also possiby wan't to become a DM at some point. I fint the best way to entertain these people is to show them how everything works. Rather than telling them how to do things, let the try to work out some of the stuff, so they remember it, and understand how it works more. For these people, to much knollege doesn't ruin the enjoyment, it makes it better.
The second type of people are just normal players. The have reached there potential, and are content to have you as DM. For these people, you need well designed dungeons, and lots of monsters. You also shouldn't reveal to much about how your working things out, as it adds to the tension for them. For example, when your doing you rolls for random monsters, or rolls for monsters nearby hearing the group, don't let them know thats what your rolling for. Occasionally, you may wan't to even make a false roll, to throw them off, and make sure they don't recognise any patterns.
The third type of people are temporary players. These are people who are only there because there friends are, or because they have nothing better to do. If you have a group of people like this, it makes your life either easy, or like hell. If your a perfectionist, or are a DM with a playable character, then you may strugle with these people, and i advise you look for another group. If however, you find yourself short of time, or have a stressfull life, then these are the perfect group. All that you need to do to keep these people happy, is to have a interesting, but not complex storyline, have lots of powerfull items, and this bit is important LOWER THE NEEDED EXP FOR THE NEXT LVL. You will find that these type of people will rush through campaines, and will also go through characters quicker than normal. You may find that a character dies every week so because of a rash mistake. If this is happening, you can either lower the needed exp for each lvl, so they get the full experience of the game... or as much as they can, anyway, lol; or you keep major traps and battles out of your campaine, errasing all real threats from your characters lives. This allows the characters to reach a higher lvl than they normally would- possibly even reaching the lvl of a normal player- before they start again.
i hope this helps
