Also I feel like most of the time with tricks like this, unless you're a machine then the spot will dictate a lot - every once in a while you'll run into specific ledges that are the perfect height and shape for a specific variation and then you'll get results 10x faster than if you were consistently trying every possible kind of move on more or less adequate random ledges.
Like always, such good advice.
There are certain ledges I can bigspin fs nose pretty comfortably, then I'll go to some other ledge and I'm missing every single one. Some attempts they begin flipping over and it's like I've completely lost the trick. Height and angle of the ground (amongst other things) play a big factor in these tricks. After a while you'll be able to feel this out and not stress over every ledge.
The main tip I can give, which sounds so simple, but is so true in this case, is to really just commit. You can't half ass a pop shuv nosegrind or fakie shuv nosegrind. Anytime I try feel one of these tricks out (by trying to put only one foot one for example) I get a bad shinner. Keep a close eye on the foot you want on the ledge (eg front foot for pop shuv nosegrind) and just slam/place it in there. Usually the worst case is sticking and running out of the trick. You're less likely to get caught up with your board pin balling between your legs. That shit hurts and easily puts you off the trick.
I can only really do nollie/fakie/reg bs shuvs into grinds and slides. Still haven't figured out front shuv into anything. What Silhouette said about front shuvs kind of dangling in front is what puts me off committing to those. With bs shuvs I find they're easier since they spin quicker so there's less time to think and bail. Plus my front shuvs are kinda garbage compared to my pop shuvs.
Some of them you'll need to play around with angle and how much you need to pop. Pop shuv bs noseslide is a perfect example of this. It's frustrating to begin with but once you figure it out they become so fun.
If you're already doing flip in stuff just focus on the shuv in tricks you want. I've never done a pop shuv 50 or 5-0 (that I can recall) or bigspin boardslide in my life (definitely haven't done one of these). If I have the right ledge I'll do pop shuv nosegrind and bigspin fs nose all day long. Pop shuv nosegrind is up there with nollie crook; it's one of the best feeling ledge tricks.