First, find the feeding area...the riffle, run, pool you want to target and make up your mind you're going to work it thoroughly. Rig for depth. This means adding or subtracting weight and/or raising or lowering the indicator is going to be your new "job". I want to try to bump the bottom, but I'll be aware that fish may be suspended mid-depth. I'll change depth when the fish show me their location. 

Second, (really three key aspects to remember)...Cast an open loop, cover the water thoroughly, keep the indicator well-mended above the leader. Well-mended means the indicator is floating above or slightly upstream of the fly.

Third, check your rig often for tangles. Use the appropriate size indicator for the size water you are fishing. Use a short, abrupt hook set at the slightest movement of the indicator.