Do I need anything more than Script Extender before starting downloading mods or am I ready to go?

[PATENT]

only SE just like in Skyrim or do I have to install something more?

[Crystal Sharrd]

Script Extender isn't necessary to use all mods. I don't have Script Extender yet I have several mods.

[Lem]

You definitely want to install and use NMM to manage mods. Many of the big mods have NMM install scripts letting you choose various options. Manual installation of mods with options is... tedious.

Only a small fraction of mods use script extender, but 'Scrap Everything' does and that mod is practically required for settlement building. Also, by launching the game from the script extender and setting F4 to only update on launch, you can avoid updating the game until you're ready. Script extender doesn't seem to trigger steam's update for Fallout 4.

[dragongodofgames]

go see Gopher(youtube). get LOOT it can help. on the mod front i recomend Sim Settlements and the addons https://www.nexusmods.com/fallout4/mods/searchresults/?src_order=1&src_sort=0&src_view=1&src_tab=1&src_name=sim__settlements&src_language=0&src_showadult=1&ignoreCF=0&page=1&pUp=1