Choosing a lender. Call two or three lenders and ask to be "pre-qualified." They will ask you a series of questions, and in a few minutes, they will give you an estimate of how much you can borrow. Ask questions about interest rates and mortgage products too.
Select one lender, and take the next step, which is to make formal loan application to get "pre-approved." A pre-approved mortgage can be helpful when you are ready to make an offer on a home. Do not select the lender based entirely on the interest rate and product, as this could change by the time that you are ready to lock-in your rate and product. Generally, you are not able to lock-in to a rate and product until you have a signed sales contract and are within 60 days of closing.
Here are some experienced lenders that past clients of mine have used and have been very satisfied with.