Skyrim is a modding dream. Mods can literally enhance the game beyond what was expected, most use the base system as it was designed, but not fully taken advantage of. Things like HDT which add physics to anything from hair to bodies to capes that actually flow around the character vs programmed moves....and many more things.
STEAM workshop is a great place for mods.. however to really mod Skyrim you have to ' know ' it takes more than SUBSCRIBE for most mods. My little barrel thing here is just a little add in.. most of the ' real ' mods you see are going to require you have some basic things added. STEAM does not give you a warning or info pop up like many mod sites do.

There are a few good mod sites.. but I ll keep using NEXUS as a reference, for two big reasons.
1. They are safe. ( and free.. you do not have to donate, subscribe etc.. you will see a page when you sign up about donations.. at the bottom is the free join. IT CHANGES nothing except limits what you can do with your profile etc.. it has nothing to do with your downloads.. what server etc... and they are part of the Forever Free )
2. They provide the Nexus Mod Manager which is a versatile tool that gets you started and modding your things in easy.

But some things you need to just get going.
First make sure you have all the latest updates for Skyrim. Since those are STEAM.. no worries.

Now go to NEXUS and at the top center of the page and find INSTALL NMM < Version whatever it is now > http://www.nexusmods.com/games/?

Now once that is installed make sure you have these two if nothing else installed.

https://steamhost.cn/app/365720/ SKSE The script extender. It allows Skyrim to use scripts that were not open at release, and the additon of new ones. You need to launch Skyrim via the SKSE Play button once you have it.

http://www.nexusmods.com/skyrim/mods/3863/? SkyUI Obviously a new interface, but more.

Now if your really going to mod the game.. this list.

http://www.nexusmods.com/skyrim/mods/19/? Unofficial Patch for Skyrim. You really want this.

http://www.nexusmods.com/skyrim/mods/71214/? Unofficial Patch for Legendary Version.. want it.

Now make sure anywhere you go to download a mod.. dont just hit download.. like at Nexus they have a tab labaled FILES.. click that.. most mods have many files for use. They are listed in most up to date, different body types.. HDT vs no HDT.. just look there before download.. you will see.

Another reason for nexus as a starter point.. if a mod has other requirements, a warning window usually pops up to show you the checklist of what you need to make it work. Like HDT HEELS for a mod or two that change shoes / boots to actually be heels.. vs warping the body bones..

http://www.nexusmods.com/skyrim/mods/24898/? Racial Compatability. Allows extensive use of various race mods. Allows the game to see the races that never existed basically.

http://www.nexusmods.com/skyrim/mods/33526/? Race pre cache. Mucho needed for more than a few race mods. Succubus doesnt care so far as I ve seen.. but once you get one to work.. you most likely will want more races.. so you need this.

http://www.nexusmods.com/skyrim/mods/12951/? Enhanced Character Editor. ( find a body you like first. I use CBBE HDT. Which is by Caliente.. also easy to find on Nexus. You can get nude, non nude.. NEVER NUDE.. versions of most bodies. HDT and XP32 skeletons allow for physics and animations of endless variety. )


http://loot.github.io/ LOOT The mod load organizer.. Let it do the load order work for you. When your just getting started dont worry over the dirty messages etc.. those are telling you of things that might be duplicates in mods between mods.. it will also link you to TES5Edit / cleaner.. A great tool.. but dont use it until your familiar with modding.. you can easily remove critical mod and game files by not knowing what your doing.

http://www.nexusmods.com/skyrim/mods/11811/? FNIS MUST HAVE for animation mods. Any mod you add or remove with animations you must run this program to tell Skyrim what the heck is going on.. or your player and NPC's tend to stand around staring at each other..

These are just the really basic things to get you going.. I may even have forgotten something that someone will say is critical.. and it could be..

Hope this helps..