Yeah, don't get talked into buying ridiculously tight rock boots, particularly on easy to middle grade routes, you simply don't need to have your toes crammed painfully into a shoe two sizes down on your normal. You need a fit that's snug - your foot shouldn't move around at all - but not painful. They will stretch a little, but lined shoes and those with rubber slingshot rands don't give that much. For some reason, shop assistants used to be obsessed with selling boots as tight as they could. Some sort of macho thing, it's pointless, they'll just hurt your feet and won't do anything for your climbing.
I'd also steer clear of the weird, radical slipper-type things as a beginner. You'll find that they have thin, flexible soles and probably won't offer enough support for your feet, FiveTen and Scarpa both offer a decent compromise between performance and comfort, other brands to consider would be Boreal and La Sportiva, but there are other decent brands around too.
Try lots of different boots on and go for the ones that feel right on your foot. Some let your big toe lie straight, others tend to cram your toes into the middle, depends on what shape your feet are. Oh, and don't worry about what size the box says they are, just buy the ones that are the right size for you.
Your best ally with all this is a good climbing shop with knowledgeable staff and a good range of different shoes plus, ideally, a mini-wall to to try them out.