Today I was in an open trail area flying near the foot hills hear in Southern California. I was out 1900 feet and up 150 feet when I started hearing the faint sound of an helicopter. In a matter of a minute or so he's all most over my head. I do not know what elevation he was at but it sure seemed to be under 400 feet. I think he saw me because he did a 360 circle continued going west and away from me. What's the normal elevation that copters fly at? What's the best thing to do? Is it better to drop the elevation or to hold my position (In other words not move from original location)? Or is there any other actions that could have been considered?