For the front, replace the stock pogo sticks with either aftermarket shocks, or on a budget, shocks from a Banshee. The banshee shocks have a progressive rate spring, which will ride better on the trails.
If you keep it stock, the shocks will ride smoothest at the weakest preload, but in my opinion it performs better all-around at a medium setting. I can't stand it on the softest setting because it allows way too much lean in the corners and off-camber situations.
The rear will take trial and error. Set it up too extreme in either direction and it's going to ride like crap. If it's too stiff it's obviously going to bounce around and wear you out, but the same can happen if it's too soft. It'll bottom out easier if the preload is too weak - every inch of sag in the suspension is another inch of travel that you lose to smooth out the bumps on the trails. If the rebound rate is too slow it'll pack up across the fast rocky sections and have it bouncing all over the place again, but if the rebound is too fast it'll spring you back up too quick. It just takes some trial and error to find that happy medium. Try setting the spring preload so the rear of the quad sags 3-4 inches when you sit down on the seat. That will give you a good base point, and you can make adjustments from there as needed.