These days most people request a Good Faith Estimate (GFE), but have no clue what to look for on the GFE. Make sure you request a GFE that has ALL fees estimated and disclosed. This includes: origination points, processing, lender, appraisal, title, escrow... ALL FEES... especially the Yield Spread Premium or YSP.
If you know that you will be moving in 3 to 5 years, you might want to consider refinancing to a 3 or 5 year ARM (adjustable rate mortgage). These loans typically have a much lower rate that a traditional fixed rate loan such as a 30 year fixed, but they do have a fixed rate for the first 3 or 5 years of the loan. This will enable you to benefit from the lower rate, but you won't ever have to worry about the risk of a rate adjustment because you will be selling the home before the fixed-rate period ends.
Use a mortgage broker. A mortgage broker will show you mortgage products from different banks and mortgage providers. Pick a mortgage broker carefully. If the broker works directly for a company that offers financial products, make sure he shows you clearly why one of these products is better. Mortgage brokers also get a commission on their sales. Find out what the broker's services include and if he charges any fees. Many brokers do not charge fees beyond their commission. Also check the broker's credentials.
Refinancing is not the only way to decrease the term of your mortgage. By paying a little extra on principal each month, you will pay off the loan sooner and reduce the term of your loan. For example, adding $50 each month to your principal payment on the 30-year loan above reduces the term by 3 years and saves you more than $27,000 in interest costs.