I suggest using Mod Organizer. Different people have different opinions on mod managers, but I started out using NMM...after having to totally reinstall everything three times, I gave up and made the switch. It is a little less user friendly, and a little more of a pain to set up, but it will save you countless hours of frustration. The beauty of MO is that if you ever need to remove a mod, or reinstall a mod, nothing is ever broken. This is because MO uses a virtual file structure so that the Skyrim\Data folder is never touched and stays clean.
- http://wiki.step-project.com/Mod_Organizer#Recommendations.
- http://wiki.step-project.com/Guide:Mod_Organizer.
You will need to use https://loot.github.io/ to sort your load order.
The below advice assumes you have all DLC (really almost a necessity nowadays):
Use the http://www.nexusmods.com/skyrim/mods/71214/?. Other "essential" mods are the http://www.nexusmods.com/skyrim/mods/31255/? (assuming you have downloaded the High Resolution Textures from Steam) and http://www.nexusmods.com/skyrim/mods/3863/?. Some good graphics mods are http://www.nexusmods.com/skyrim/mods/45807/? and http://www.nexusmods.com/skyrim/mods/141/?. A good weather mod is http://www.nexusmods.com/skyrim/mods/73937/?. A couple good lighting mods that work well together are http://www.nexusmods.com/skyrim/mods/59733/? and http://www.nexusmods.com/skyrim/mods/17609/?.
However, I would strongly suggest following a guide for your first time modding. It will show you all the basic steps you need to do for a stable game, and properly introduce you to all the necessary tools (such as what I mentioned above, MO and LOOT, as well as ENBoost, SKSE, FNIS, etc.).
I would recommend either http://wiki.step-project.com/STEP:2.2.9.2 or http://wiki.step-project.com/User:Neovalen/Skyrim_Revisited_-_Legendary_Edition. Both are good in their own way...STEP stays closer to vanilla, while making everything better. Very user friendly, and if you don't have the best computer it is perfect. SR:LE includes a lot more gameplay mods and more intensive graphics. It deviates from vanilla Skyrim play a bit. Slightly more difficult, but still decently user friendly. Requires a fairly new computer with a good graphics card.
You can't go wrong with either guide. Both have forums where you can ask questions if you get stuck or are confused. Either will teach you about modding "the right way", and then after that you can much more easily choose your own set of mods and have confidence that your game isn't go to blow up or go crazy with bugs.
Anyway, good luck, and happy modding!