FAIL-SAFE INSTALL PROCEDURE FOR BEGINNERS
0) Update Skyrim to 1.5 or higher version.
1) For everything below use ORIGINAL GAME LAUNCHER
2) Start Skyrim, load game, dismiss all followers,type show playerfollowercount and if it shows 0, save game, Quit.
3) Disable all mods affecting follower limit or mechanic (ILF, Mullti followers, TCG and any other) then uninstall them.
4) Delete any loose pex files in DATA/SCRIPTS folder that are on the list i have linked(LIST OF BAD PEX FILES )
5) Start Skyrim, load game, save game, Quit
6) Install UFO, position UFO.esp at the lowest place.
7) Start Skyrim, load game, save, Win.
8)After this Install you can use whichever launcher/manager you please should you choose to.

UNINSTALL:
1) MAJOR THING:(Only If You Do Not Want To Play UFO Anymore) Before removing you need to dismiss all your followers and go to Riverwood. On the river island there talk to Tina the Firefly. Yes she's a firefly. Only when you get dialog saying "It is done, please quit game and remove UFO files." can you make a save and uninstall.
--WHY?-- If you don't, all follower will have Outfit=None remembered in a save and with no other follower outfit setting mod you'll get a lot of naked peoples. This is unfortunately the only way i can make this mod compatible with other mods that change actor forms, without having to worry about compatible files or setting Outfit=None manually in other mods.
2) MAJOR THING:Also dismiss followers before talking to Tina and removing the mod. Otherwise extra followers above the one allowed by vanilla game will be non-hireable with vanilla settings.

UPDATING UFO
Unless stated otherwise download updated files, extract them to data folder and when prompted replace the old ones in there.
Check in ORIGINAL GAME LAUNCHER that UFO is still lowest in load order(or where you had it before updating).
Start Game.
Extra:
Updating Directly from versions 1.0(a - f) to version 1.0g and higher using Full UNINSTALL (otherwise the above extract,replace,play should be used) :
1) Dismiss followers, talk to TIna till you get msg to remove UFO. Save
2)Disable UFO, load then save.
3)Extract new files to data folder replacing old UFO files, enable UFO in Original Game launcher, place it last in load order(or in place it was before being disabled). Load save. Done

TROUBLESHOOT
--USE ORIGINAL GAME LAUNCHER--
1) If you have problems after doing Fail Safe Install Procedure for Beginners, following it to the letter, you may have:
a) Bad Save Game
Do Fail Safe Install Procedure on a different save.
Start new game.
Contact mod authors whose mods you uninstalled and got problem from
b) You have a mod conflict.
1)Disable ALL mods you have and leave only UFO enabled
2)Rename DATA/SCRIPTS folder to DATA/0SCRIPTS
3)Load a save game you are sure is not corrupted by old mos being uninstalled and you have no followers with you.

COMPATIBILITY:
0) Any mod that does not modify dialogfollower quest/script
1) If you load below UFO, you can use mods for followers. Unless they have dialogfollower limitation from 0)
2) Custom follower mods by default get - Level UP dialog, Display STATs dialog, More Followers at Once, Followers can Ride and can have full inventory control by telling: You could dress better.