Ive modded my Skyrim 5 times now and up to 86 gigs Modding IS the game in some ways
As for whats best.... man... tough call but heres a few pointers..
1. Nexus mod manager. it will make installing and uninstalling SO much easier.
2.READ the full descriptions before installing.
3. Seriously , read the descriptions or you will break your game.
4. Go to nexus and check out the pictures on these 2 body type mods ; UNP and CBBE
There are more but these two are the top two in ratings , stability , compatibility etc.
Once you have made your choice follow their recomendations for Armour and weapon ( etc ) mods.
This will keep things compatible and running smoothly as long as you follow the directions.
Not all mods install the same way.
5. the 2K textures mod is great and can be later enhanced using ENB. I urge you to not install ENB until you have the game just how you want it.
6. Save game bloat is an issue... avoid a major pain in the A&& by not making 535 of them.
7. make backups of your data folder, ( if you are going to use BOSS make sure to have your backup hidden otherwise it may detect/mixmatch the wrong files )
8.Read the descriptions carefully ; when they say it's incompatible with another mod , they really really do mean it.
9. Install SKSE , it is the backbone of countless game changing mods. There are some good youtube vids that are total step by step. ( painfully so at times but thats a good thing to the new guys )
10. insert reading stuff being important comment here plz <<<<---------------------------
I know I really beat the dead horse on the reading thing but god , if you only knew how many hours I've spent trying to help someone fix what shouldn't have gotten broken to start with.
Ive helped quite a few people turn their vanilla Skyrim into a truly next gen game with enhanced A.I. , 4k textures , new animations etc etc etc.
In my experience the crashes and such people have are almost always because of their "TL;DR" mentality.
Feel free to PM for help , or to just kick the can around about Skyrim.