First off respect yourself and don't act like a slut. Don't throw yourself at any bloke. Don't wear to much make up just keep it natural. If you gonna wear clothes that are reveiling ie mini skirts hot pants or skimpy tops do it with pride and don't show your parts off.
With your question it seems like you find sluts very attractive.:) I haven't known a guy who finds sluts attractive.
Best way to be attractive is by being yourself. Reason for this is that you want a guy to like you for real you not the TYPE of you. When someone will like you for you then that's the kind of relationship will last long.
Well by doing simple things like working out, focusing on getting great looking skin, wearing pretty natural looking make-up, and doing your hair nicely can make your overall appearance prettier and enhance your looks. Clothing wise, keep it simple and classy. The girl next door look always works.
off the bat, the ways in which you'll appear 'easy' is through your clothing and makeup. so don't buy slutty clothing that sticks to your body or is super short and don't wear dramatic makeup (i.e., glossy red lips, excessive eyeliner). you're young... :p dress cute, be yourself... that's attractive in itself.