I've also found it helpful to shoot on a heavy solid surface, some distance from the amps, and yes, sandbag the hell out of your sticks. If you have to be near the amps, a heavier duty tripod will help. Also, a tripod with fewer risers can help, since the tripod itself is less hollow.
And lastly, if you can get yourself a pair of wooden sticks, you'll be good as gold.