The thing with escaping from side mount, you can't be flat on your back. You need to be on your side (facing your opponent) with your bottom knee pulled in, nad your bottom elbow pulled in, under your opp. trying to keep space between you and your opp.
here is just 2 options.
Option 1: pull guard.
to do this, from the above positioning, When your Opp. creates some space, you want to buck as hard as you can, immediately pull you bottom leg under your opponent,
As you buck and pulling your leg under, use your bottom arm to push on Opp hip, upwards, keeping space to get your leg under. (also, use your opposite leg to PUSH yoursefl under to help get you to guard position).
NOTE: to do this, from the beginning position, your opp must have their arm over your head, with elbow behind your head. NOT underhooking your head. if it is an underhooked situation, you must first buck and try and position thier arm/elbow behind your head.
Not sure who this is, but it is a good example: http://www.youtube.com/watch?v=3hk_IewhGXI&NR=1
Option 2: Shrimp out, to double leg
to do this, when your opp creates space, ebby backwards to get your hips turned over. continue to ebby and turn your hips until you are facing your opp. From here, you move forward into a double leg. most likely ending up in their guard.
best piece of advice i can offer. You know when you are about to end up in side control. so start escaping BEFORE you end up flat on your back. go straight to being on your side, facing the Opp ball up with your knee and elbow in..............