First off, a guy is going to like you no matter what you're wearing (within reason). Basically dress for the event you're going to, i.e. a nice dress to a dance/club, jeans and a tee for mini golf. Secondly, dress what compliments you. If you're busty show that off with a hot top (don't show too much though). If you have nice legs, wear shorts or skirts. If you have a butt, wear some nice jeans.
Hair: I prefer straighter hair, but when a girl goes out, I like it if she does her hair up, sometimes that means curls, sometimes not, depends on what we're doing, how nice it is, etc.
Shoes: Vans are cute now, heels when going out. sandals if you live in a warmer climate and you get to show off your painted toes. haha
Brands: Most of the mall brands are fine, amercrombie, pac sun (personal favorite), hot topic (in moderation), etc etc. Pick a store who's clothes you like the most and see if they look good on you. if they do and you like the store, build a wardrobe off their clothes. Style is all about setting a tone. If you were an ambercrombie girl, you'd wear jeans, jean shorts, tees, and lighter colors. If you didn't set a tone one day you'd wear jeans and a tee and the next you're wearing thigh high boots and black makeup all over your face, people will think you're weird (unless you dress like that every day then there will be some guys who like you haha). Sometimes you'll have a tone, but you can buy stuff from other stores. As a guy, that's what I often do, jeans from this store, boxers from that one, tees from everywhere.
Jewelry: I think the key is moderation, meaning less is more. You don't have to wear some flavor flav clock on your neck to get attention. Honestly some earrings (just say no to hoops), a bracelet, and maybe a necklace. Again match the jewelery to what you're wearing, and to what compliments you. Don't wear a choker if you're wearing a high cut sweater, or gold chains over a tshit, that's just faux pas. Some girls wear rings, but I'm not a fan of them. hands should be ring free, well except for that one important one. Ankle bracelets are hot when in a bathing suit, if pulled off correctly, but as a guy I'd know she's not going to go swimming, but is checking out guys and tanning. A belly button piercing can be hot to display while in a bikini but I think everyone's preference on that is different. I could go either way. Any arm bands or waist chains are lame, and/or odd. Stay away from the odd ones.
Accessories: just like jewelry, less is more, and you have to match to what you're wearing. Watches, belts, etc are all nice, but only in relation to what you're wearing and it depends on the type of item it is. Accessories are just that accessories. They need to compliment what you're wearing, not draw away from it.
Never wear something that will draw too much attention from your face, you want guys to notice your "features" but ultimately look back to your eyes. So don't show off too much cleavage or too much legs, unless at the beach, then by all means show off that sexy body.
straight (hah) 25yo guy. We notice things...