I've noticed that the BIGGEST help with crafting is level. The higher the level, the more noticeable the success rate is.
After that, I've noticed that craftsmanship skill does help (but not just +1 or +2, but adding a lot to notice a little). I notice this when I upgrade my tool (since it has both craftsmanship skills).

Now, as for whether or not to use Magic vs Non-Magic Craftsmanship, I have yet to see an official/prooven post indicating when one is used and what not.

As for 'Stats' (int, mind, etc). Unsure how truly effective they are (and in what quantity they need to be in order to be effective).

I will note this:
Crafting the exact same thing 10 times (same location, direction, moon phase, weather, etc, for those who are superstitous) I notice a myriad of different results. Results ranging from: 5 success in a row, to 10 failures in a row. I notice fails giving almost as much quality as a success, and success happening regardless of orb colour.

The ONLY things I feel confident about are:
Continuously using 'careful' increases chance of destabilizing element. (Not guaranteed, I can fail 10 times in a row with no destabilizing, or destabilize on first attempt).

Continuously using 'wait' can result in stabilizing element. (Not guaranteed, I can use wait once and stabalize, or use wait 4 times with no stabalization, or use wait 3 times, then standard, then wait 3 times, and still not be stabalized). AND I can even use 'Careful' while destabalized and end up stabilized again. Actually, I'm starting to wonder if this is just random too.

And, well, that's all I feel confident about. That, and I can just spam standard synth, ignore everything, and still end up with roughly the same result averaged over time.