If you had a crush on a friend, what would you do to start building interest?

Met this girl last year nearly dated but didn't, kept as friends though.

I'm seeing her next month as myself her are spending the weekend together with a few friends, we have some fun energy where I've sprinkled in some slight flirty jibes to keep conversations entertaining teasing her but I know I just need to work on flirting more to get her attention.

Whats subtle things I can do to slowly build up things?

If you had a crush on a friend, what would you do to start building interest?
Post Opinion