#1 Wipe your fork tubes down before every ride, keep-em clean, try to avoid mud drying on them durring beer breaks, if you need too, pour your BUDDIES beer on them to keep em clean. Ive seen some guys spray them with wd40 and some with brake clean before they ride, what ever you want as long as they are clean. Depending on riding conditions I say pull dust seal down every 10 or so rides,( maybe more maybe less). I Pull the dust seal down wipe all the grease out(q-tip or rag), spray it clean with wd40, work the fork up and down to help get the old grease down on the tube to clean away. I use a- DOW CORNING 55 grease, its designed for O-rings and it slightly swells the seal. Swelling isnt bad on an o-ring. I have stopped a couple small seal leaks doing this. If you can find that grease, get it, works excellent. IMO brake clean will dry out the seal after repeated use. But some magazines use brake clean on fork seal quick fixes.
Thats just what I do, hope it helps