Untick all of my mods in my mod manager and boot Skyrim.

Ensure all mods installed are using their newest versions.

When it's already happened and I'm crashing on boot or on entry to an area, I do the following.

Make sure the mods you have also have any compatibility patches made for them to interface with other mods installed.

that way, if you get a crash, you know which group of 4-5 mods to investigate.

Install your mods only 4 or 5 at a time, then see if you can load the game.

It will not only sort your load order, but it will notify you of detected conflicts before you try to run anything.

ALWAYS READ THE MOD DESCRIPTION FOR A CONFLICTS SECTION.

Keep track of which mods do what and avoid situations where two mods accomplish the same basic task.

To prevent this, I follow the following steps: Other things that can cause this include trying to load an Oldrim mod into Skyrim Special Edition, major game overhaul mods conflicting, or even a patch to Skyrim that breaks certain things. That's a really rudimentary explanation and a situation that doesn't always cause a crash, but you get the idea. Skyrim then loads A, and B, and when the assets for mod A are replaced by those from B during startup, the game crashes. Mod B replaces Pinewatch with a 12 story wizard tower. It mods Pinewatch in a way that makes sense for the mod. Mod A adds NPCs, and homes them at Pinewatch. This is why the order of how your mods load in Skyrim is important, as well. It means that one or more of your mods is malfunctioning, usually because of a conflict between two mods.

Mod organizer not working