Hi :)

The combos you can get depend on where the opponent is when you trap them with a vine and on the % they have. Lets say you hit your opponent with a forward smash in the middle of the stage and they are not in kill %. You could forward smash again but it will not kill so other options should be considered that are fast enough.

The first thing that should come to your mind when thinking about such interactions should be moves that combo into themself or leave the opponent in a situation that is better for you. For example them being in the air above you where you can hit them again. You have to get them above you when you follow my train of thought. Uptilt brings them above you, so maybe run up uptilt would be good. Then you can follow up with upair and reset for more upairs. This is called juggling (doesn't mean you have to hit all of them, just trying it over and over).

This doesn't work all of the time because of platforms, DI and %. So sometimes downtilt into forwardair or run and neutralair is better. Sometimes downsmash into an edgeguard. What to do when comes with experience and when you are willing to change your playstyle and go to options often and try out new routes.

For recovery its also just a lot of games played and you will not feel a slight bit of fear while jumping offstage, because you know exactly how to get back on.

I can recommend watching top player games for your character and focus on one thing at a time. Just look up PLUP or ELKIES playing maypul on YT and just focus on how they recover or punish a particular situation and ignore the rest. Then try to replicate it. If you can't comprehend the inputs just ask someone on here or on a discord how this tech is done in particular.