* you know something about my company and why you want to work here (visit our corp. site, interrogate the recruiter, read up on our press and know something about our space)
* you know what we're looking for and understand that we're talking to you because there's some intersection between your experience and our search criteria.
* for that intersection in the venn diagram of our candidate requirements and your resume, brush up a little so that you can speak to how you used technology X. If it was 2 years ago or less know it well... if we're talking 10 years ago being more general is fine.
* be able to describe how you got to where you are in your career and where you want to go.
* know who you're talking to in the phone screen and LISTEN to what they're asking you. i can't count how many folks i ask to describe how they built a particular solution go on to just ramble on about feature descriptions and process without ever getting to how something was built.