What do you consider "done up"?
I don't know what 'done up' means in this case. Is it too much makeup?
What is too much, what is just enough (what would you find "acceptable")?
There are times when more makeup may be necessary, a stylistic choice etc. But for more general use, I prefer when women wear little to no makeup. If they're wearing makeup, it should only accentuate what's already there - the natural beauty. Too much makeup is when you can't make out the person beneath their makeup or they look mummified.
When you see a girl with "too much" makeup on, what are your first thoughts?
That the girl is probably popular but feels deeply insecure about herself and who she is. Possibly looks to others for her identity.
If she is not wearing any at all, what are your first thoughts?
It depends on the woman. Makeup doesn't suit some women. I take note more of those who wear lots of makeup. They get my attention, but it's not one of attraction. Most women I interact with on a day-to-day basis wear no makeup (or very little). I don't know these things!
What occasions are "okay" to be done up for?
Going out somewhere, a special occasion. I don't know. They can wear it when they want. But less is more.