These are various framework and bug-fixing mods you will most likely need. They are dependencies for many mods, so it's best to get them out of the way.
Remember to always check the dependencies dropdown on the Nexus before downloading a mod.
To have the least amount of issues, please do not skip this section.
Read mod pages. Mod authors will outline specific instructions or bugs the mod may have. Lots of your issues can be solved by a simple read. Always know exactly what you're downloading.
Check dependencies. On the mod's homepage, open the requirements drop-down. Pay attention to the requirements section, not the "mods requiring this file." It is worth checking out what mods require the mod, for patches and such, but the first thing you should always look at are the requirements.
Download from the files tab. Some mods have multiple parts, multiple versions, or hotfixes which you will need to download in addition to the main file. Downloading from the files tab (instead of the button on the top right of the title bar) lets you see exactly what you need to download.
Pay attention to the version for SKSE mods. This is another reason why downloading from the files tab is important. Some SKSE mods will have multiple versions. If you have AE, download the version for 1.6.xxx, not 1.5.97. The version will be stated in the file name or description. Some SKSE mods will work on multiple versions however, so make sure you read everything. However some SKSE mods can function on all versions, regardless of your SKSE or game version. These are called NG (Next-Generation) mods. The mod page will usually state whether or not said mod is an NG version.
Check the posts and bugs tabs. These can help warn you of issues with the mod, and sometimes will include fixes and other bits of useful information.
Don't use the in-game mod manager (or Steam workshop). It lacks the most essential and bare-bones features you will need, and doesn't have support for custom tools, or even the Nexus. It is designed for console users. Ignore it on PC.
Don't annoy mod authors. They do this work for free, as a hobby, and owe you nothing.
Endorse mods you download. It's a good, free way of showing support for mods you like.
Unofficial Skyrim Special Edition Patch is the ultimate comprehensive bug-fixing mod for Skyrim. Not only do many mods require it, but it will make your game much less frustrating to play overall. The version publicly listed on the Nexus page is only supported for AE 1.6.640, all older versions are hidden by default and only accessible via direct download links. If you are using an older version, here is the download for 1.6.640 and here is the download for SE 1.5.97.
Address Library for SKSE Plugins is a dependency for most SKSE-based mods. Remember to get the correct version for your game. (We won't put these version reminders for every mod, so get into the habit of checking the files tab and downloading the correct version!)
powerofthree's Tweaks fixes bugs and includes some small game tweaks. Dependency for many mods.
powerofthree's Papyrus Extender is another SKSE framework. Dependency for many mods.
SSE Engine Fixes is a mod that fixes many bugs in the game's engine. It also enables achievements. If you find another mod that enables achievements, you don't need it, because Engine Fixes already includes it. Download the Part 1 file for the correct version, then manually download part 2 and extract to your game directory (Steam/steamapps/common/Skyrim Special Edition).
SkyUI gives the user a cleaner and easier-to-use interface that is more suited for PC. You can use a mod like Hide SkyUI if you really want the vanilla interface, however the main mod is still necessary because it adds the Mod Configuration Menu, or MCM. This MCM, accessible through your system tab, lets you configure mods in-game, if the mod includes a menu for it.
MCM Helper contains support for mod customization. A lot of mods require this to customize things in-game. MCM Menu can be accessed from (Journal Menu (J) > System > Mod Configuration). SkyUI is a requirement for MCM. While the mod has other long-term support versions, it doesn't have the 1.6.640 version listed. Here is the MCM Helper 1.6.640 version.
More Informative Console improves the console and shows information on objects or actors that you have selected. Very useful for debugging.
SSE Display Tweaks is a noticeable performance booster, in addition to having options for VSync, FPS limiting, and window scaling. It enables windowed borderless mode by default. The performance section has a few tweaks for it.
.NET Script Framework is a useful mod that enables crash logs, in addition to being a dependency for other mods. NSF does not work on AE! To enable crash logs on AE , use this crash logger.
These are some more common dependencies.
This list is not exhaustive. This repository has lists of commonly needed/recommended mods in different categories. However, it is as of now, outdated. It is being worked on. It still is a good place to navigate for recommended mods.
Yeah, Skyrim has bugs. Luckily we can do something about it. These mods are needed in addition to USSEP.
Unofficial Skyrim Modder's Patch - This mod fixes some more niche issues and has some improvements that aren't necessarily bug fixes, so make sure you read the mod page to see exactly what it does and what mods it replaces. Get some patches for it here.
Keyboard Shortcuts Fix - You don't really need the DLL loader version, you can just get the SKSE one.
Combat Music Fix SKSE - AE version here, or Papyrus version here. Latest AE Version here.
This page of the repository includes a long list of bug fixes. It still isn't exhaustive. Some of them are included in USMP. Also as previously mentioned, it's currently outdated and being worked on. However it can still be used as a source to find said type of mods.
Have the base dependencies and framework mods installed
Have a better idea of how installing mods works
Know good modding habits and methods