The main function of labels on blog entries is to associate that entry with other similar ones, so please, when you post your challenge entry, there really should only be two labels. The first one should be the one for that challenge, no variants, no additions, so enter it as "Challenge 999", not "Ch 999", or "Challenge #999" or "Challenge 999 Bling". The other label can be your name, and you should always use the same name, no initial added if your first post didn't have it, and similarly for nicknames; be consistent. (And do use labels, unlabeled entries get lost in blog limbo-land!)
What not to use? Don't use the challenge theme, the title of the piece, the technique used, or as I've already said, a variant on the challenge number or your name.
I will be editing existing posts, bit by bit, to standardize labels (in my other life, I'm a computer programmer, and this process is called "normalizing"!), but you can do this in your own posts by clicking on the pencil to edit your post and its labels. Thanks.