Check out
this thread. I found it very helpful when I was installing Tutu. Make sure you've got the order of install correct and that you've done a full install of the entire BG series. Basically,
Full Install of BG1
Full Install of BG ToSC
TOSC Patch
Full Install of BG2
Full Install of BG2: ToB (if you've got it)
ToB patch
Easy Tutu
EasyTutu Hotfixes
EasyTutu DeGreenifier
EasyTutu NPC Kit mod (if you want it)
Tutu Fixes
Then additional mods.....