Plan. Execute. Vanish.

Plan. Be prepared, research, recon, and have contigencies. Be ready for the operation or project.
Execute. Once you have the facts and a simple plan, go for it. Don't want until everything is perfect. It never is. However, execution should be flawless, as much as you can make it happen. Execution decides the success or failure of the operation.
Vanish. Once you are done, leave. Do not leave anything behind. Don't provide clues as to what you did or how you did it. Be gone.