The cast should be made just upstream of the trout's vision window. A trout in a good feeding rhythm usually remains fairly close to the surface and its cone of vision will be quite small, so a cast just a few feet above its position will be sufficient. Too much of a lead may cause the fly to drag by the time it reaches the trout's position. Try to determine if the fish has a preference for taking the naturals to one side of its body or right down the middle. This will affect where the fly should be laid.
Every cast is important.
The first is often the most difficult, as the proper line length must be calculated. It seems to be of less consequence to err on the short side. Try to keep the false casts to a minimum and angled back so as not to cast directly over the fish's head. In the fly's final approach to the water, reach out to allow the line to run the proper distance. A 9-foot rod provides greater leverage with this manoeuver.