Hit up a friend who's a good player and bring them along.
Like the other poster said, try all the guitars in your price range and under.
If you have to pick out one on your own, buy the tuner first, and just go into the store and start plinking. Just try out a couple of guitars in the models that are priced in reach. Tune the guitar and play a couple of chords. Play it until the tuning stabilizes-- listen to the tone as you do. Play all the chords you know, and try some barre chords if you know those. Most store guitars are tuned and the strings stretched. If not, the strings will likely be shiny new and it may be hard to judge the tone through that extra brightness. They will also go out of tune easily if really new.
Now pick up that other guitar of the same model, and do the same thing.
By that point, you should have a favorite between the two. Ask yourself why.
Is the construction slightly better? Or does the guitar just seem to fall into tune more easily, and also sounds better to your ear?
Don't buy a guitar the first time you visit; just play them. Explain to the staff that you will buy when you find the right one, and you plan to take your time. Within about an hour, you should be able to pick out differences in the sound of the guitars beyond the tuning and new strings. You are now listening for the sound of the wood.
If you can't yet pick out which guitar is better between two identical models, play a couple more of the same model, and try to pick out the one thats the clunker, that sounds or plays the worst. This is easier. Then ask yourself why that one sucks, and try to pick the best of the bunch.
If you need a clue, try playing one of the nice models in the store, and compare it to the ones you were just playing. Then go back again and try out those same models.
After a couple of visits you should be able to pick out a decent guitar from the models in your price bracket.
If not, maybe the bass?