Maximum keywords 50. Many (and I) do this. But is it right?
Some stocks recommended only 15-20 keywords. If more, then "these will actually hurt your ranking". Shatterstock doesn't write like that, but maybe...
I try to attribute words to each photo by groups (for example): What, Where, Act, Emotion, Amount, Colour, Environment, Age etc. But the result (financial) does not please me at all.
Maybe my approach to keywords is wrong?