I found a great article listing tips that real estate experts had for first time buyers looking for financing.
One piece of advice that I have always given is to find a mortgage broker you trust and work well with together. Spend the time early on with that broker to figure out what you can afford and what product is best for you. Then, when he/she gives you their pricing, shop around their offer. Out of curtsy, you should give them the chance to match your best offer. That being said, this is business and a huge financial commitment, I would almost always go with the best rate/payment/plan.