>>76362264 (OP)Do as many sets of as many reps as possible on crunches and leg raises.
Find a way to incorporate weight on both exercises if possible.
Leg/Knee raises you could do hanging as well as on the ground.
Again try to incorporate weight and progressively increase it.
Even tho I said as many sets and reps, try not to go insane on day one, do 5 sets of both exercises and if you are not sore the next day repeat. Increase weight and sets when you feel like you can.
Experiment with yourself and your abilities.