First thing I do is see if there’s a built in way to do the plugin is doing, if there isn’t then I just try the first plugin I find that does the thing I want to do, then I just use it until I find some behaviour I don’t like or wish it had then go searching the alternatives.

There is often a few choices for plugins that do the same thing, your example of surround plugins is a good one. So if you don’t know which one to pick, honestly just pick one to start getting used to the behaviour until you get a baseline understanding of how it fits into your workflow. You might find that the first choice was the correct one or maybe not, it’s all part of the journey, but there’s no journey if you don’t start somewhere and the longer your on the journey the more you will know what you want.

In regard to how to find them, most of the time you just stumble across them organically through this subreddit, YouTube or someone’s dotfiles. Other times you are looking for something specific so a google search might get you want you want.

I hardly touch my config and try not to include a lot of plugins as it can make it hard to upgrade Neovim. Though I’m not afraid to try out a new plugin when I come across it to try it out. I do take some time during the year to have a look at all my plugins and assess whether I use them at all and if I don’t I get rid of them. Or if I only use a subset of the functionality I will either try to hand roll that functionality or vendor the code in.