I am a beginner who wants to L-sit, should I begin the appropriate progressions on the floor, or on parelletes (I have both)? Paralletes seems slightly easier. Thanks.
Sit down on the ground with your legs straight in front of you. Put your hands next to your thighs and push yourself up (straight arms!), leaving your feet on the ground. Hold for the assigned time period.
Do a foot supported L-sit, but raise one of your legs up from the ground.
Sit down on the floor with your legs bent (about 90 degree angle at the knee, 45 degree angle at the hip). Put your hands slightly in front of your butt and push yourself up (straight arms!).
Advanced Tuck L-sit or One-Leg L-sit
Either tuck less than before (extend your legs outwards), or stay tucked and extend only one leg straight like in a real L-sit.
I can't push up! Are my arms too short? Should I use paralletes?
No, your arms are not too short to do an L-sit. You just lack the ability to push down through the shoulders (depress the scapula), or to compress enough (see here for a demonstration of maximum compression)). The foot-supported L-sit from the progression will help with the former, compression work will help with the latter.
My upper leg cramps up and hurts! What do I do?
Massage it out and continue onwards. It'll get better with time.