@preciousklay With regard specifically to L-sits, they require a number of basic skills combined for a single movement. The very first things you will need to establish is while you are sitting in the L-sit position, are you able to lift your feet and calves off the ground? Also, if you hold your arms parallel to your legs, are you then capable of "bouncing" the entirety of your legs off the ground? (Legs should rise and fall simultaneously, the bounce should be roughly the speed of a basketball bounce, and ideally you want to get most of your hamstring off the ground so that at the height of the "bounce" only your glutes are touching the ground.)
Next, you need to establish if you have the upper body and lower abdominal strength to lift your bum off the ground. To start with, sit in the L-sit position with your hands flat on the floor and your arms lined up with the front of your torso. Lean forward slightly, and allowing your heels to remain on the ground, push into it with your hands, and tense your abdominal muscles to hold your legs in place. If you are not there yet, no worries. It is possible to make this easier by altering from an L-sit to a straddle sit. The muscles engaged are very similar, and by starting with a slightly easier exercise you allow yourself to both build the required muscle and gain a sense of achievement, which is important for consistency and goal-oriented workouts.
You also mentioned handstands as a specific skill. I don't know where you are at proficiency wise with this as you did not specify. There are a number of ways to begin training handstands. One of the first things a person learning handstands needs to do is become confident with their hands being their only contact with the ground (or other object). There is a very simple jump (the name of which has escaped me for now) which involves placing your hands flat on the floor, and then using a gentle jumping motion to attempt to get the hips aligned over the shoulders. The legs can remain in a tucked position for this exercise, and tucked is preferable for this as it takes the focus away from extension and places it upon body awareness. If you are not sure if you are hitting the correct position, you can either attempt this against a wall - if you're hitting the correct position, your hips and maybe the top of your bum will contact the wall, as well as your back and shoulders - or film yourself, then analyse the footage. This exercise is not intended to be held in position for a long time, 1 - 2 seconds is plenty.
Walls are your friend! The two main ways of implementing walls in handstand training are to do a full handstand with your back against the wall (although this does not guarantee good form in how you enter the handstand), or either cartwheeling or shimmying your body against the wall so that your stomach is touching it. If you are confident with cartwheels, this is definitely the easier way to get into position, otherwise start with your hands on the ground and your feet against the wall and walk your body in towards it. How big or small the steps you take are doesn't really matter, this is just a locomotion to get into position, and the position itself is the priority. When using walls, it is a great opportunity to work on your endurance - how long you can hold the position, and how long your brain can accept being inverted. This naturally varies for individuals but can be built. Also while in position with your stomach against the wall, once you have gained some confidence you can start doing things like having only one hand on the ground, and alternating which hand. You can also explore what it feels like to do a straddle handstand, for example. The easiest way to get down from the stomach against the wall position is to roll out of it. If you do not have the space or you do not really know how to do this, a controlled step down similar to a cartwheel exit is serviceable.
There are a few main types of press-ups, and a crap load of variations. Different ways of positioning hands, elbows, and legs, change which muscles are being focused on. Instead of listing all the types I can think of here, I think it may benefit you more to do a little of your own looking. You know which things you want to target, so you can base your choices on that. Also, in terms of press-ups, being able to do 5 - 10 is all good, and you will likely find that when you alter the type of press-up you are performing that you will be able to do more reps than you realise.
Anyway, good luck with your exercising.
