Don't bother dresing sexy for a guy. Dress sexy for you! If you feel good, you will look good, and guys will notice. Wear something that you feel pretty and confident in, but don't worry about showing skin. If you want some inspiration, think of a celebrity who's sense of style you admire, and who has a similar body type to yours, and google some images of outfits that they wear that make them look pretty without being "slutty".
You don't need to have a perfect body or wardrobe to look good. Just show off your best features and leave the rest to the imagination. And remember, don't just focus on how your chest, waist, and hips look. Other parts of your body can be sexy too!
For example, here's my formula. When I go out to the bar, I usually wear a pair of skinnies with some boots, a cowel-neck top, and a fitted leather jacket. The shirt doesn't show off a lot of cleavage, but the drapping style is flattering on my smaller frame. Skinny jeans are flattering on my long legs, and boots give me good posture. I often wear dangly earings, because I have a pixie cut and the earings draw attention to my neck. While some girls might consider their boobs, hips, etc to be their best feature, I'm aware that mine are my legs and slender neck, so I try and make use of this. This outfit makes me feel nice, and I get more attention from guys dressed this way than I do in a minidress or any other outfit. You just need to find your style that shows off how cute you are, and guys will be drawn to you. They can see that you're a woman, so they only need a few peices to put the puzzle together. Good luck!