Most Helpful Girl
I don't think a gril could be insulted by a guy asking her out. She may reject you but why should she be insulted? If you don't want to scare her away just suggest something casual like hanging out with other people or helping her with something etc.
Most Helpful Guy
-Be interested in her, not only her body (she's not a bag of meat.
-Be sure there is no professional / hierarchic / authority interference between the two of you.
-Take into account the context : some moments are just not made to hit on people, and it depends a lot on the person you're trying to ask out.
-Accept rejection with a smile, respect and without insisting.
Those are the 4 rules I can think of right now... If you follow them things will should be all right, but of course I'm willing to hear more suggestions, especially from women and feminists ^^