Getting into trad climbing - any tips?

I'm getting into trad climbing, after quite a few years of indoor and outdoor sport and bouldering. I'm very aware that trad climbing involves more risk, especially if you climb above your ability and/or are bad/inexperienced at placing runners. Does anyone here have tips on how best to practice protecting a route to the point where you feel safe enough to climb a difficult crux with only trad protection below you?