hair clueless

hey.. I seriously need help. I'm completely clueless when it comes to hair, and it shows. I'm getting a haircut next week, potentially the first real "style" I've ever had in my life, and I want to be able to actually make it look nice.. so some help is greatly appreciated.

Some background:
my hair is brown, mid-back length, not really straight, not really wavy. It's basically the worst of both worlds: it has the bland style of straight hair, but the frizz and tangles of wavy hair. when i air-dry it it goes a little wavy, but never nice enough to actually wear out.

All my life I've basically been in a cycle between shoulder length and butt-length, no bangs. 95% of the time I pull it back into a ponytail. occasionally, i braid it or put it in a bun instead. if i wear it down it's all tangled, and hot on my neck, and generally doesn't look so good.

my hair styling routine is basically wash it with whatever cheap stuff i buy at the drug store and comb it. i've bought silicone, mousse, wax, hairspray, gel, a straightener, a blowdryer, fancy brushes etc, but it never really ends up looking any different with those so i generally don't bother using them. the only effective thing i've ever done is putting a bunch of silicone on, and brushing it over and over with my fingers (and blowdrying, though that doesn't seem to have much effect) and the next day it's maybe less tangled.

when i get my hair cut, the stylist straightens it and it's all smooth and nice until i wash it again, so i know m y hair has the potential, it's just me.

i'd like to make it wavier, because i think it has the ability.. i just don't know how. but it holds styles really well.. i used to sometimes sleep with pincurls after washing it, and without styling products, my hair would stay curly for 2 days. like, day 1 would be keri russel curly, and day two i'd brush it out and it would be j.lo wavy. someone said my hair is almost like black hair because it holds styles really well.. especially since it's more on the fine side than coarse.

next week, i'm cutting my hair to about my chin and getting highlights, so ponytails may be out of the picture. i want to be able to actually do something to make my hair look good, so i need advice!! help this hair clueless girl make something of herself!