I could go in so much harder when it comes to organizing but right now I fight to keep it simple.
Body Parts -
-Full Avis
-Mesh Body
-Mesh Head
-Eyes
-Skin
-Tatoos
Other(there is ALWAYS an other folder tossed into ever category just to hid random things.)
Clothes -
Accessories
-Head
-Face/Ears
-Hands
-Ankles
-Makeup
-Necklaces
-Other
Tops
Bottoms
-Pants
-Skirts
-Shorts
-Omega
-Other
Dresses
Outfits (items that have come with a top and bottom already)
Halloween
Christmas
Hair (this probably should be Body Parts, but..)
Shoes
Other
-Objects
Furniture
Decor
Boxed
Yard
Other
-Animations
AOs
Poses(a terrible, terrible mess)
Dances
Sits
Stands
Other
... I think those are the main areas I use, then there are just random things everywhere in the many 'Other' folders, throughout. Whenever I buy anything new I spend time opening and trying the stuff on and then put it in a somewhat proper place, just to declutter. I also have a hoarding problem, when it comes to group gifts and event gifts and free things.. so I get all these items and rarely remember what everything is, and have not gotten the chance to wear even 50% of everything I have yet. What a shame lol. I'm prepared for any event or occasion but I wouldn't know it, until I dig deep into my inventory and discover things I didn't even know I had.