There's nothing profound and certainly nothing original here. These are simply common sense principles that we all - including myself - need to remember when out on the stream.
Before working any stretch of water stop and examine it carefully. Note what insects may or may not be present in the air or on the water and plan your strategy before proceeding.
Move with stealth at all times. Keep your pace along the bank and in the water smooth and quiet.
Visualize where fish will be holding in each piece of water you plan to fish. Systematically fish the water from the tail section upstream so that you will have a chance to take more than one fish from any given area.
Be precise with your casts. A successful fisherman will be able to place each cast within at least a serving platter sized section of the river where he is aiming. One single sloppy cast can ruin a good stretch of water.
At all costs minimize or completely eliminate your false casts. There are no flying trout. The more time your fly spends in the water, the greater your chance of success - and the less chance there is that the trout will see your line.
If you must false cast, do not do so directly over your target. Not only will the fish be alerted by seeing the line in the air, it will also be frightened by the water droplets being shaken on the surface as the line snaps above it.
Except for certain pocket water conditions always try to make your fly hit the water first, followed by the leader, followed by the line.
Cast as short a distance as you can consistent with avoiding detection by your quarry. Short casts permit superior line control and accuracy. Cast within your comfort zone. Move your feet before you lengthen your line.
Do not yank the fly from the water at the end of each drift. Remove it smoothly and softly so as not to disturb your prey.
Vary your tactics and casting technique to fit the conditions. Nothing works perfectly every time. If you use commercially tied flies, maybe modify them slightly so that they appear less heavily dressed and slightly different than the original store bought version. Then occasionally fish them in a somewhat different manner than normally recommended.