The first thing you need to do is speak to a loan officer. They can tell you how much you can afford, so you are not wasting you time looking at houses out of you price range. Also if you find a good one if your credit is not where it needs to be, they can help you with a plan to get it there. Next find a good Realtor, normally we don't charge the buyers anything for our services. As far as credit score that answer varies depending on the company. Remember that FHA loans are coming back and they don't weigh heavily on credit scores. check itout and good luck!