Flirting can be fun, but keep it in perspective. Just because you have great banter with someone doesn't mean that there is any real substance there for you to build a relationship on. If you want to get more serious with someone you've been flirting with, then you have to get more serious. Start having real conversations about real issues, and stop tossing those double entendres around. Find out if they are really as interesting as you think they are.