I'll tell you the facts of my most successful party.
It was in 1997, a halloween party on a Saturday night.
I made invitations on a computer that had a word search game on it. The word search was to try to find the most number of mythological gods and goddess names, and the person who found the most would win a prize.
The party was set to have free liquor and mixed drinks, and people were invited to bring their own beer or cider.
Of course it was also a costume party and there was a prize offered for the best costume by popular vote.
I had live music being played in the attic of our 3 flat for the whole night by a band thrown together by a friend of mine who was a regular at the night club I went to.
I had Halloween party favors ordered via mail order, things like spider rings, orange and black silly straws and various other oddities and I had halloween candy in a big jack-o-lantern bowl sitting just inside the door.
I distributed my invitations at two different nightclubs I was a regular at, I had printed out 100 invitations, and with my friends help they were all distrubuted to nightclub REGULARS, no strangers, but not all close friends.
With 100 invitations, I expected 30 to show up.
In the end 40+ showed up to the party and it was a smash... a great success and the only big party I ever threw. It was wild but not crazy, and everyone had fun.
I attribute the party's success to the fact that it was a Halloween party, but it wasn't thrown on actual Halloween (Which is when people usually went to night clubs for costume contests) Also the live music and free alcohol helped and judging by the number on people who turned in the word search for the contest, I'm guessing that helped too. People, even adults, like games and contests, almost as much as they like alcohol.
Bear in mind that the pool of people I was drawing from at the nightclubs I went to, were Goths, Punks, and New Wave fans... so the Halloween theme was very popular, and the friends I had enlisted to hand out invitations knew a LOT of people.
So that's "best party" story.... hope you can get some ideas from it.