Color, Sketch, Other, sounds like a good way to go. You can always list in the drawings' description that it's personal. I've not understood why people would separate the drawings that were commissioned for them to draw from their normal work other then it's easier for the customer to find the work.

I think both are a good idea, having a folder for sketches and separated colour folders.

Personally I like Commission, Personal, Gift, with sub folders for "Including my characters" c:

I think Commission- Personal - Other would be best for you. ^_^

Personally I organize it was type, for example: Chibi, Icons, Refsheets, General, Fetishes, Personal etc

The commission-personal-other is good for people finding what characters belong to who, but a more specific color-sketch-chibi-icons-pinup and such sub folders would be a nice addition. though i'm not entirely sure if subfolders exist here

if your going to post preview stuff for tail heat, probably have one marked previews.

Definitely have a sketch folder cause that is what I search for most of the time

Gallery and Scraps are the only two folders you'll ever need!

And here was me thinking this was going to be a gripe about not being able to sort folder-order. ;)

I arranged by year, bu that was when I dumped old stuff across. I take ages finishing works, so tend to do a lot of work-in-progress uploads. So for me a WIP folder is a good one.

Here the ability to split between sketches and scraps might be a good one. A sketch can be a finished work, and you may not wish it to be mixed with abandoned bits or entertaining doodles.

Really I'm all about function, so really it's whatever makes things easier and better organized for your purposes.

I will say I wish more artists would have a separate folder or section for art that's exclusive to the site (meaning anything the artists uploads only to that site) would make it easier to keep up on all the latest new content.