Equalize the track by dropping a linear phase EQ plug-in onto the Master channel of your techno track. Putting the EQ first in the mastering chain ensures that subsequent plug-ins won't amplify undesirable frequencies. Add a high-pass filter at 30 Hz: frequencies below 30 Hz are all but inaudible and can create a "muddy" feeling in your final mix.
Add more punch to the kick drum by boosting the frequencies around 60 Hz slightly. Increase the volume in the 40 to 200 Hz range to bring out the bass. Experiment with boosting and cutting other frequencies to highlight desirable sounds and attenuate undesirable ones. Don't add or remove more than a few decibels from any frequency: If you find that the track needs such drastic alteration, it's time to go back and re-mix the parts.
Put a compressor on the master channel of your techno track. The compressor evens out the dynamic range of the song, essentially making the track sound louder. For a pumping techno sound, turn the "Attack" and "Release" knobs all the way to the left, then gradually turn them to the right until you find the best sound. Set the "Ratio" to between "2:1" and "3:1"; this creates smooth compression rather than drastically changing the overall sound of the track.
Insert a stereo effect plug-in after the compressor. Stereo effects can help the techno track sound wider and fuller by panning different frequencies left and right. As with equalization, use stereo effects in moderation: If you find yourself making significant changes to the stereo field, go back and change the mix.
Drop a limiter onto the Master channel to finish the mastering chain. The limiter ensures that the volume of the techno track never falls below a certain level. Use a fast attack and release on the limiter to preserve a sense of space in the track. Adjust the input and output knobs so that the volume meter hits the target level --- usually between -2 and 0 decibels --- but doesn't go over it. Listen closely to the track, go back and re-adjust the settings in every plug-in until you attain the ideal result.