Politely. And preferably without a cheesy line – those don’t tend to go over well in most situations. I always recommend asking someone to hang out over coffee on a first date. It’s low pressure, can be short if it’s not going well, long if it is, and there are no awkward moments where someone has their mouth full of food trying to answer a question. Although I will admit to liking the line, “If you were a library book, I would check you out.”