hey! lets see..the amount of people you invite all depends. How many people are your parents allowing? If theres no limit, just invite all of your friends that you hang out with. I always think around 20 or 30 is a good amount cause its always fun..probably around 20. Boys? Depends also. Do you know a lot of guyz that are your friends or that you would invite to your party? if so invite them. If not then dont bother cause dont ya think it would be kind of weird having like 5 boys there with all of these girls? you can do a ton of things...make pizza-roast marshmellows-dance-play truth or dare(not to bad tho)-GET THE SIBLINGS OUT IF YA HAVE ANY! lol that just may be because my little sister is buggin me now. -have water ballon fites- go in the pool? if ya have 1- do makeovers- do hair- and other stuff