Good luck, i 'm crap at plastering.

I'd like to recommend seejanedrill on youtube as she covers a lot of topics and is pretty good at explaining stuff. But that's not enough for me to get close to competent.

I think plastering might be one of those things that one just needs lots of practice and experience to get good at. That said if you don't care that it's not perfectly flat, I don't think you have to be that good.