Probably one of the most misunderstood issues when folks are buying a house is that the buyer's haven't got their financing in place! It is so important to get that done right up front! How? DANGER DANGER DANGER!!!! Do NOT go to an online come-on to get a "pre-approved" mortgage! It seems like it would be the right thing to do, but in the end it usually falls apart. What is happening is there are many "mortgage originators" who will issue an approval very quickly, but we find that the rules and requirements change further down the road... many times when it is too late to easily back out of the purchase, so the buyer is almost "forced" into proceeding with less than favorable terms!
So how do you avoid this? When you contact your Realtor ask him or her for a few names of local lending firms that they have a relationship with. Then when you call them, tell them you're shopping mortgages, and that Steve, your Realtor, suggested you contact them. These originators are WAY more reliable!
So, follow your real estate agent's lead... ask them who would be a couple of good mortgage companies to contact!