Basically, this is my first time trying it. A bit shaky.

But I read of people "training" just to be able to do an L-Sit just for 5-10 seconds, yet I haven't done anything for it, except pull-ups and chin-ups (they make my abs feel like jelly sometimes, so they must have helped). So I was thinking maybe my form is incorrect?

I know raising my legs higher is harder (V-Sit), but they look parallel, except for when they drop slightly.

Advice on form and training welcome. My aim is to hold a good form L-Sit for 60 seconds. Currently I just go for a max hold every night and aim for 5 seconds more than before - I did 25 seconds the other day.

looks good! idk i cant tell if your sitting with ur shoulders low as possible keep ur chin up really high in the highest lock out range of motion , dont sink into your shoulders , sit with a solid top form, no sinking into your shoulders with lockout, lockout in the arms and lock out at the peak of you shoulders also, no shoulder sinking with arms locked out , idk those are my training habits just helping out