First things first, most people start with a triangulation type of stabilizer. This is where you tie the stabilizer jacks in the front and rear to the frame of the camper. There are various products for this- SteadyFast, JT StrongArms, BAL, and others.
After that, people often use a between-the-wheel chock. RotoChocks used to be my go to, but they were a family business that is no more. There are others, though.
You can do like OldCoot and others and add stabilizers just in front of the axles.
And finally, you can eliminate the bounce from someone coming up the exterior steps by adding a positive connection to the ground under the bottom stop (either a jack, feet, or go crazy: swap steps entirely).
See if this article helps you any:
http://learntorv.com/shake-shake-sha...stabilization/
I personally like SteadyFast stabilizers:
http://learntorv.com/product-review-...t-stabilizers/
And, if you do go nuts and swap steps, you'll find that the extra stability is just one of the features that make them super nice.
http://learntorv.com/product-review-...n-by-torklift/