If you are worried about trying things you might not like you will miss out on a lot a great beer.
Absolute truth right there.
To the OP,
It takes time, just pick up a few things that interest you every time your at the store, you'll start learning what styles you like, and it will get easier and easier to pick up a new brew. You'll also expand your knowledge base enough, that you can read up on specific beers online, and get a decent grasp of what something will probably taste like.
In addition to that, at least in my experience, your tastes will change while you are exploring different styles. I used to be really into stouts and porters, now I'm in an IPA and Red Ale phase. I've always loved Barleywines and Belgium beers, though.
You'll begin to appreciate and enjoy a broader spectrum of beer, even if it's something you wouldn't buy again. In the past year or so, I can really only think of maybe 4-5 beers that I really hated, and that's with tasting hundreds of beers. I have a book that records ONLY the beers I really like, and it's at 215+ beers right now. If I included all the beers I've ever tried, it would probably be 350-400.
I've even gone back to beers that, in the past, I wasn't fond of, and some I now like quite a bit.
Just be patient, stay open to new styles and breweries, and try everything you can afford/obtain.
Good luck.