I know this through trail and error
I know this through being the person that someone tried to make jealous. Honesty, it worked... but it backfired. His flirtatiousness with every girl but me hurt my self-esteem, and I took it as a sign to back off. A year later, I'm no longer interested, he lets slip "oh, I was just trying to make you jealous"...wtf?
That's really unfortunate o.O
Yep. This, like most aspects of relationships and courting, have an optimization curve which explains the relationship between effectiveness and quantity of jealousy.