@carina2111 Frogstand (crow pose) is easy to start to try and there's no "getting good at it" practice other than doing it, but you need to take some precautions when you do the movement and ease into it when you're starting.
So start to get into the pose, but keep one leg sort of back / or keep your balance back, so you can balance with one of your big toes. Practice
lightly tapping forward into the balance, and use that leg/toe to fall back on if you start to lose your balance. The most important thing with this when starting to learn imo is learning to fall. You don't want to injure yourself, and falling forward is the best way to injure yourself. Ideally, when you feel yourself starting to lose balance, bring one leg back, which should bring your balance falling back, but use your fingers to lever yourself back if you need it. If you find yourself unable to do any of this and you feel you're going forward, falling straight down is the next best option, drop your legs off your arms straight down into a kneeling position (have a mat or towel under there so you don't hurt your knees if this becomes a common occurrence).
The big thing with this pose is that you shouldn't do any fast movements. Tapping forward from a toe balanced position to the full arm balance needs to be gentle, and don't worry if you tend to fall back into the toe balance. As you learn to balance like that, you'll get more comfortable. Like most Yoga poses, to get better, you just do it for as long as you can hold it, comes out of it, wait a bit, and do it again. I tend to just repeat it once if I'm doing it daily with other exercises (but I hold it around 30 seconds), but if I'm doing a yoga day, I'll do it 3 times. This is a move you can practice as often as you want. Every day won't hurt you because it's a balance exercise (though it may be tough at first if you don't have the shoulder strength for maintaining the pose, there's still no motion involved so go at it every day if you want). This is one of those poses that once you learn how to do, you'll likely retain the ability to do it (I just started working out recently after a 4 year or so hiatus after having my daughter, and this pose is something I've easily incorporated back into my exercise even with all that extra weight).
One arm pushup is likely the same as any other pushup if you can't do one: find a type of pushup that's as close as possible to what you're trying to do and get good at that, then start doing negatives of the difficult one. Sometimes you don't even need to do negatives if you get good enough at the close one. For one hand pushups, get good at pushups of
good form with a close hand grip. Then look online for the form for a one hand pushup (definitely start with wide feet), and see if you can do one. If you can't, do the negative routine. Get into the top position and lower yourself as slowly as you can, making sure you gracefully fall if you can't maintain it. Don't push yourself up, but get back into the top position and lower yourself as slow as you can. Do sets of negatives like you would sets of pushups. Negatives work for so, so many bodyweight exercises. I can't recommend them enough for people struggling with pullups, particularly one arm pullups.
I can't really recommend anything for a
front tuck lever, but looking at it, it seems like it's another thing you just start getting into that position and holding it for as long as you can. Not sure how the mechanics play out, but negatives might help (as in, get into the tucked position however you can and slowly go down, eventually you'll be able to pull yourself up into the tucked position). I'd guess getting good at pullups help. I used to practice front levers like this, so I'm guessing it's similar.
With respect to your question about doing a bunch of these at once, look at what major muscle groups are being used and what the range of motion is. Crow / frog can be done every day. Some days, particularly after shoulder exercises, you won't be able to hold it as long, but there's no motion involved and it's just balance. Pushups exercise the chest, shoulder and tricep, so be cognizant of what else you're doing on different days. Levers are pretty much core and back muscles (someone correct me on that one if I'm wrong, as there may be chest utilization too), so again, be cognizant of what you're doing on different days. The biggest thing to worry about is rest, so practice one arm pushups on chest / tricep days but not the day after. You can do levers on back days, but don't do them the day after a back day.
