I think a bit of subtlety goes a long way. Not needing to do the "giggling, flirting" thing, I do however think "bearing your soul" to him so to speak would more than likely send him running. Boys like to chase, you can be a bit more aggressive when you know for sure there's something happening. But simply "telling him how it is" I imagine will make him lose interest very quickly. Flirting has its merits, it suggests you could be interested but it also doesn't make you seem desperate.