Most Helpful Guy
You can't. Woman knows within 5 mins whether she wants to fuck you or not. Friend zone is just another way a woman can pass on the boyfriend duties (except sex) to men, and get you doing stuff for her without her doing anything for you but allowing you to be in her presence and not act like a stuck up bitch when you are around her.
Most Helpful Girl
Say "Do you want to go on a date sometime as more than friends?" If they say yes that's great! And if they say no you still have a good friend. Win-win.