What should I do to improve the quality of the screen capture? I'm creating videos to post to YouTube.

My videos are about some jobs I do on the computer.

I watched some of my videos posted and that the quality of the video capture was not very good and clear.

What should I do to improve the quality of the screen capture?

To use better software? 

I'm using Windows Media Encoder
Windows Media Encoder creates files in wmv format (I guess), which is highly compressed. Make sure you follow the YouTube recommendations