I'd actually recommend you play your first full game modless (plain vanilla).
That should give you a feel for what the vanilla game is like, and what you like and don't like about it, so you'll be in much better shape to make your own decisions as to which mods look interesting or useful to you.
Then I'd experiment with mods to find out which one you like or not. Some of the most popular mods are probably not too bad to start with (as long as they're not full game overhaul mods or ones that add a ton of content, as those will almost certainly be completely overwhelming for a newbie.. they can be overwhelming even for advanced players).
Also, I'd start with just a single mod or two, and learn how to use those before adding more. It's easy to go mod-crazy, but that's useless unless you actually know how to use them. So learn a mod or two at a time, and then get a couple more.
There are usually videos on at least the most useful and popular mods out there, so those should be of great help in learning how to use them... but nothing beats trying them yourself.
For me personally, the top three absolutely essential mods are Fill4Me, Squeak Through, and Todo List. Don't expect to be blown away by these mods.. they're very small and very simple utility mods.
These days I actually play with hundreds of mods, so the three above won't even give you a small taste of what's possible.. they just cure a couple of annoyances, and add a tiny bit of useful functionality that I personally can't live without. But sooo muuch more is possible!