I always put the forearm of the gun on the front rest, not the barrel. Also, never put the forearm on a rigid surface, needs to have some give in it or it will change the point of impact. In the field also never put the forearm on a rigid rest to shoot. Put you hand between the forearm and the rest (tree, rock, etc.) although a soft daypack works well too.

Sandbags have always worked best for me at the range. Easiest to change and maintain a point of impact for me. Although rice bags would probably work as well. I usually have one under thebutt and 2 under the forearm.