Basically always had this issue. Since about 2013 I've never gotten back(or even close to) where I was before I had to take the break. Not gonna lie it's insanely frustrating mentally knowing what you should be able to do and your body not being able to do it anymore. I just first try to make sure I'm physically up to whatever I'm gonna be trying. I don't know your condition but you gotta at least be able to run, jump and survive a slam.
Then I just have an idea of like a pyramid of stuff to do. Like Ollie is the best then manual, boardslide, 5050, noseslide then next is nosemanny,nosegrind, 5-0 lipslide, tailslide, crooked. There's all flips and 180s and switch whatever too I might add in if I'm feeling it but I try to be efficient. Just be kinda smooth get it done, go home. Not get stuck on something for an hour.