I've set up a commission queue tracker with Trello
https://trello.com/b/RQD5ljRs/commissions

Waitlist/Negotiations: This is where I'll mark anyone I'm talking to about commissions or otherwise working with before payment has be made.

To do: this is all the commissions that have been confirmed and paid or prizes or such I owe

Sketched, inked, colored, shaded: all the process steps so you can see the progress.