The followings hints seems simple to follow but they are not! It depends on your personality, your skills on interviews and many other things.
A technical interview can be a difficult step during the hiring process. We often know some concept but we cannot explain some mechanism because we simply apply it in practice.
On stackoverflow job section, you will always see if a company follow all the points of the Joel test.
The company don't necessarily follow all points.
Some essential books about the whole interview process.