Here are a few things that I gathered from various sources while looking for a house:

• Get pre-qualified for a loan. Check out different banks/brokers to see how large of a mortgage you qualify for (in my case I qualified for a lot more than I was willing to take on, but at least I knew the lender would be willing to provide a mortgage on the houses I was looking at). This should also give you an idea of what you'd expect to get for an interest rate.
• Upfront costs to expect: -Earnest Money (to "hold" the house during negotiations) ~1% of purchase price. Home inpsection ~$300. Closing costs ~3% of purchase price, but sometimes sellers cover some/all of this. Down payment - amount is up to you, but like Josh said the 20% avoids paying extra interest/insurance.
• I looked at a lot of houses on my own before even talking to a realtor so I had an idea of what was in my price range and what I liked. On weekends I'd check the paper for open houses and during the week I'd pick up fliers to compare prices and $/sq ft for different neighborhoods.
• Create a list of features you must have, want to have, and would like to have. Also create a list of things that could be deal breakers for you. That way when you talk to your realtor you can give them an idea of what's important to you (# bedrooms, certain neighborhoods, or even something like a real fireplace) so they can help narrow down lists. Then when you go look at houses you have your priorities listed out and can see how the house stacks up.

Here's a website (www.homebuyingguide.org) that a realtor recommended for first time buyers to become acquainted with the process. in Anchorage there are workshops put on by AHFC for home buysers and they have their course material online (www.ahfc.state.ak.us). Could be useful.