Fallout 4 mod load order

In general as GeneralMike said, use a 3rd party tool on PC. When running a fairly to heavily modded game, the built-in version from Bethesda sometime crashes as it forgets to activate DLCs.

As a general rule for organization:

• official esm (normal as they have to be on top)
• Unofficial Patches should be the first esms after the official files
• other esm

esps in following scheme

• non-conflicting texture changes
• item additions
• new locations
• new stuff/effect etc
• overhauls to game mechanics
• compatibility patches between mods

Consider using LOOT, a tool to sort load order, and using a mod organizer like Nexus Mod Manager (IMHO at the moment the only viable solution as long as Mod Organizer has no stable version for Fallout4)

First off, you will probably want to use a separate mod organizer program of some kind. FO4 has some build-in mod support OOTB, but there are a lot of tools out there on the internets that make modding much easier, especially if you want to run a heavily modded game. Depending on which one you use, there will be prompts or features that help you work with mod conflicts and load priorities. Check out their documentation for how that all works. I use Nexus Mod Manager, and that's what I've based my answer on - if you use another tool, YMMV.

So, with that said, I can think of 3 major things to consider when trying to determine load order:

1. Do what the mod author says. Most mod creators will include some form of "Installation Instructions" text (either in a description on the site/service you download the mod from, or as a separate .txt file that comes with the mod files, etc.) - heed their advice above all else.

If the mod author doesn't include any instructions, or they don't help with your particular mod combination, then consider:

2. Mod requirements. Some mods will require other mods to be active, or they don't work. If Mod B requires Mod A, typically (but not always, see 1. above) you want to load Mod A first, then Mod B after.

3. Mod conflicts. Sometimes you will find multiple mods that make the same or overlapping changes. For example, Mod A may add new textures for water and clouds, and Mod B may add new textures for grass and water. Since both mods will affect the water textures, these mods will conflict. Whichever mod is loaded LAST will be the one that you will see the effects of in game - so if you want the water textures from Mod A, load Mod B first, then Mod A after.