I've modded extensively all the recent bethesda games. (Morrowind, Oblivion, Fallout 3 and New Vegas, Fallout 4,skyrim). It's an amazing experience, super addictive, and a ton of fun and you will learn a lot. Use to post some about it in this thread.
http://www.thebore.com/forum/index.php?topic=42946.0The only suggestion I would give is to start slow rather than expansive. Start with 20 mods or 30 mods or some much more manageable number even up to say 50 mods. The problem with starting with a shitload of mods is that understanding how shit conflicts with each other is insanely daunting when you have that many variables going on. If something breaks it becomes almost impossible to debug and fix when you have a million mods going at once especially when you are new to the process and don't really quite understand it. And just inherently the more mods you add, the more unstable your game will be. There is just no way around that fact despite what anyone else tells you. Learning to mod is a slow tedious experience that you only get better at over time by seeing what works and what doesn't works. It took me at least about 10 times modding skyrim before I was comfortable with actually trying to seriously play that version of the game in anything resembling a serious playthrough because some mods won't break visible stuff until you get further into the game. But it was a hell of a lot of fun (and frustrating) going through that process.
I would also suggest following a guide the first time. There are plenty of those on the internet either on the skyrim modding nexus or on step
https://wiki.step-project.com/Main_PageYou can modify the process however you want, but following doing somebody else's footsteps will be an easier process than just brute forcing it yourself solely.
As far as mods, my absolutely favorite skyrim mod is Legacy of the Dragonborn.
https://www.nexusmods.com/skyrimspecialedition/mods/11802Just a brilliant framework and focus for a certain type of playthrough.
Don't be upset or surprised if you fail the first few times at trying to put together a stable mod list. Just use the experience for the next setup.
I'm probably going to end up doing an oblivion modding playthrough sometime in the upcoming months myself.