don't just ask "to go out" in general. they/she/whatever can't easily refuse such a blanket offer.
ask to go out for something specific. then they can refuse and say they're not in the mood for that.
if they do that, do not immediately follow up with something else they'll have to refuse.
if they want to spend time, and it's just the specific suggestion, they would suggest something else to counter.
always give people an "out".