Squier Fender Strat is a good starting point. Pop along to a shop and try one out. You might also want to try a Yamaha Pacifica. Put some time into picking out a practice/rehearsal amp. If you're playing in a bedroom a Pod or an amp with modelling built in would be a good investment. Try out the guitars you fancy with the basic amp you can afford. Look for a good all round bluesy sound from the two, metal distortion can be dialled in later.
Look for a neck and body that feel right in you hands, easy to move with and hold. Look for the sound you want. Single coils give a wailing lead sound but cheap ones can pick up buzz in a nasty way. Humbuckers are more for rhythmn work but cheap ones can be fuzzy muzzy. There are some guitars which combine both single coil and humbuckers. Avoid archtops, semis and hollowbody's unless you're desperate for a jazz/rockabilly sound.
Above all pick up the instrument, heft it, pluck the strings and ask to plug in. When you find the right one it'll sing out loud and clear.
'The sound of the city seems to disappear'