Michael's, JoAnns and other places sell "risers" which are about 6-8 inches tall, with ridges on the top to keep table legs in them. Set your table legs on these and now you have a raised table. I've seen others who stick the legs of the folding tables into PVC pipes which are cut to the desired height. I like the risers because they are easy to put on and off, so you can have the table for stand-up or sit-down use, whatever.