Part decorations are organised as follow:
First: printed parts ordered by LEGO official name number
Second: printed parts without ref number
Third: stickers

I agree that sometimes, it can be a bit hard to find the next available number. I mainly use the "New Parts" section or navigate through the folders. I could make a little tool to find out this data more easily. At least now, it tells you now when you upload a new decoration files or save a new reference that is already existing.

I always start with the "New Parts" section, which works fine for common parts (e.g. minifigs) but for other parts this doesn't work out and it takes me five minutes or so to find out the next available number. Some help with this would be appreciated. 😉

I'm very sorry, but this still sucks. The least problem is, that parts do not appear in the order they're supposed to do, but the most recent part sometimes doesn't appear at all for whatever reason (> we search by counting up numbers until not found for next free) or it's in some other category. This drains time by forcing decal makers to find the latest number and afterwards rename source files after a failed upload attempt. I really wonder how difficult it could be to show somewhere, what the latest added decal number of a particular model part is, whatever category it can be found in.

Or better show next free number to further avoid confusion. Of course there's only a few decal makers, but small things like this do eat up time better invested in making decals. Of course I'm open to other suggestions, perhaps I need to adjust my workflow.