Hey - you're in Brum, there are no excuses!
Welcome to the forum - I'm a Brummie GG
For starters, do the Primark, Mark 1 and other cheap stores to get a feel of what you like. They sell absolutely everything in these places at really low prices. I recently saw bra and knicker sets for a quid in Primark in all colours (that's around 50c for you Americans)!!
How to buy - you take a look, pick up what you fancy and take it to the check out
Do you have any close GG friends? If so, pick one you can trust and ask her to help you out. My best friend at school was a guy and he came to me for help with applying make-up (mom walked in and told us off - only because we were doing it 'wrong', lol).
For shoes, try Oasis - they have some really sexy stuff there, I used to love shopping there when I was a lot younger but I'd never get away with it now, hehe. They do shoes in all sizes and so you'd find something that won't kill you and even shoes and boots specifically made for men but are definitely very girly. Also, it is a sort of fetishy place, all gothic and punk and so you generally find that they're more accepting of people on the edge of the 'norm'.
**Wishing I could get to Brum for some serious shopping soon**
Have fun!!
PS: You MUST do the rag market, my friend used to get some real bargains there (as did I actually, lol).