Use an annealed beading tool, when bead setting colored stones. You will have to reshape the tip often; however, the softer tool will not abrade the stone as easily if you happen to rub against it while forming the bead.
If a channel is too wide for the stones you are setting tap down on the top of the channel wall without the stones in place. This will spread the metal closing the channel. Then, anneal the mounting to soften the channel wall prior to setting the stones.
Use bent chain nose pliers to set stones with, instead of regular chain nose pliers. Then, your hand and the body of the pliers will be out of your line of sight, allowing you a better view of the work you are doing.
When setting a colored center stone with side diamonds, make certain that the diamonds do not touch the center stone. If one of the diamonds comes loose and rubs against the center stone, it will cut a groove into the stone.
When flush setting use a burnisher with a flat tip, rather than a rounded tip. The rounded tip will not allow you to burnish the metal at the point of contact with the stone, which may cause difficulty tightening the stone. A flat tipped burnisher makes full contact with the metal allowing you to burnish the metal tightly against the stone.