When you build or extend your house, you're highly aware of the importance of finding the right contractor, negotiating the price to include all known costs upfront and getting a time line nailed down.
Ask for Referrals and Check References
A successful web project requires the same. Find a web developer by asking your colleagues and associates who they worked with and whether they'll refer their web development company or look for sites you like and ask the owners who developed their site and whether it was a good experience.
A Case for a full-service Internet Marketing Company
An important point to remember is that a web designer and a web programmer or developer are separate roles requiring different skills - just like a builder and an architect. In most cases freelancers specialize in one or the other, but rarely equally in both.
If you would like to discuss an online strategy, you'll again need a different skill set and may be best served talking to a full service interactive marketing agency.