Well i have a couple of good mods that i downloaded for the PC from Skyrim Nexus.
Nexus mod manager
this is very handy and i really recommend downloading and installing mods and keep track of them. You can also easily remove mods if your having trouble with them with one button.
Its a huge player hideout with allot of stuff and stats boosters so you can cheat if needed. It has a throne room,a treasure room,a garden that has lots of ingridieants,an arena in which you can fight or have other creatures fight and a lot more stuff like that.
Masters of Death - Rise of the Brotherhood
A mod that changes the dark brotherhood armor to make it more warrior like and it has plans to add a lot more to the guild.
Cloaks of Skyrim
well it adds Cloaks to Skyrim which you can easily create with leather. you can also download a thing that will give capes to some npc's around skyrim.
Stones of Barenziah Quest Markers
it add's quest markers for the thiefs guilds search for the unusual gems.
Ultimate Follower Overhaul
it makes followers more usefull. with this mod you can level your followers and recruit more than one, also you can ask them for what they are good in which will show their stats and more.
Every city has various guards oufit TS Edition
This will make guards wear diffrent armors that will fit the city they guard instead of the boring armor every guard wears.
if your computer can handle it then you should get this cause it makes whiterun feel less empty and visually better.
A Quality World Map
this will make the map allot more visible so you can actually see where your going.
well thats a start. Mods are all about your preferences. Do you want to have the game stay lore friendly or not,do you want it to look diffrent or do you just want to test stuff out. It all depends on what you want just register at the nexus and look stuff up.