Familiarize yourself with Techno music including other DJs and artists. Listen to producer/DJs such as Joey Beltram, C.J. Bolland, and Derrick May (one of the pioneers of Techno). Pay close attention to their programming and transitions as they mix.
Build up your Techno library whether you are mixing with CDs or MP3s. You can purchase music on iTunes or DJ MP3 sites. Invest in DJ remix services like Ultimix or X-mix where Top 40 and pop songs are remixed with Techno versions.
Practice mixing some of your favorite Techno tracks, and even incorporate other genres that are similar such as Progressive or Acid House. This will add some versatility to your sets and give you more music to work with. Be sure your programming is on-point--you don't want to sound like you just played record after record without having a sense of "telling a story" with the beats and sounds in each song.
Record yourself and critique your own mixes, or have friends do the same. This will help you improve as a DJ and you can get ideas for future music sets or performances.
Promote yourself by staying active in the music community. There are DJ sites or rave sites you can join for free that will be great for networking with other DJs and producers. Register for social networking sites like MySpace and Facebook. This will help you gain more exposure and popularity as a DJ.