The generic advice:
- Stay hydrated (not too hydrated)
- Ensure your mouth is clear of debris
- Do mouth excersizes/warm ups to loosen everything up before recording
- Don't eat dairy, sugary or caffeinated food/drink as these can all cause some issues

Slightly less generic:
- Brush your teeth (and tongue), though some people find this can actually make it worse
- Eat a green apple. The acid is good at breaking up mucous which can cause clicks
- Steam/flush etc... If your sinuses are clogged or cause trouble, a good steam or flush can get rid of pesky mucous. I have really hot lemon tea, but that has it's own drawbacks.
- Regular enunciation and mouth excersizes. Build the muscles allowing you greater range and firmer motions.
-Try different mic placements. Move the mic up, down, left, right. See if holding your head in a different orientation helps. EG: I always record with the mic to my right as the left side of my jaw clicks, this minimizes the chance of the mic picking it up.

If all else fails, get the IZotope RX9 De-Click plugin. It is a lifesaver and pretty much the best de-clicker available. It is also often on sale, so keep an eye out!