Need Ideas For My 13th Birthday Party :)

Ok, so I`m having my 13th birthday party, it`s in a week & I`ve invited about 15 + people, it`s going to be at my house in the afternoon but I really want a really cool/special decoration that will make all the difference but can`t think of one, and I also don`t know how to entertain my guests besides from music....and party games are kind of sad at my age, also I dont have a Wii or Playstation or anything like that so I`m really stuck!! Please help! Any ideas??