Dressing a green salad - Oil first!
Basically every lesson I see on dressing a green salad (famous chefs, etc.) has one doing all kinds of tricks for making vinaigrettes etc.
Years ago, I found (for me) the real trick was to coat the greens FIRST with some good olive oil - THEN add whatever you fancy.
If vinegar and/or salt - even in an emulsion - makes contact with the greens first - it is quickly absorbed into the cells and they can very quickly become soggy or at least lose texture.
If there is first a thin coating of oil - the salad waits till it gets chewed for the ingredients to mix - much more tasty and interesting for me.