Keep your batteries fresh, herb well cured (dry), grind fine (or very fine), never fill over the rails and shake, shake, shake between hits.
Only the surface of the mesh gets heated, only the tiny fraction of herb in direct contact can get heated enough to make vapor. Keep that part fresh, shaking does that. Weak heating of the mesh further diminishes the potential for vapor. Unless you use a PA and push it to combustion the extra power is used to make vapor directly (not pay 'overhead'), keep rotating batteries until you get the hang of it. After that you can easily do a trench on a charge, even a trench and a half.
Don't put water (moist bud) in, that robs precious vaping power, water gets first dibs on power, you have to dry it out before you get good vapor anyway so why not before? And condensed water vapor inside the box is what makes fouling happen. Being good on keeping the water out can seriously limit or even prevent fouling as many have reported here.
One last tip, don't mess with the weld of the mesh to the rails. Lots of guys have damaged theirs fussing with buildup which continues to degrade once started. It's eventually fatal.
Best advice is to experiment with technique and follow the results you like.
Regards,
OF