Flirting is all about observation and escalation. Flirting is a game of fun, it is not seduction. You do it to entertain and entice, not to get your end away.

You start with a comment, or joke, or double entendre. If your flirtee responds in kind then you progress and maybe escalate a little with another comment or joke or double entendre. What’s most important, though is the observation. If your flirtee backs down then you fucking back down too. If your flirtee misses the cue then you back down. If you’re not sure, you back down.