I always pick toon-up first. You don't get the option of getting it again until MML, and it's really useful in DG when you finally start doing buildings, facs, etc. That and it takes the longest to train.
It usually takes me longer to finish DG than the Brrgh, because unless I have a friend helping me, most of the toons are clueless and toon-upless and insist on using their pathetic sound to unlure my cogs.
So yes, toon-up always first.
The rest are always: toon-up, lure, sound, drop (don't like trap very much). On my first toon I got sound last, and I didn't like it. I was getting Cashbot HQ tasks (the mandatory ones) and no one would even take me in the coin because I only had the ahooga.