Quick Mask tool
Know Your Background Color
You can often save a lot of time masking, if you know and bear in mind
what background your masked image will be composited on. Keep your
goal in mind; when you need to get the job done, release your mind from
the constraints of perfect masking and do the bare minimum!
Refine Edge
The Refine Edge tool set is a very powerful, non-destructive set of tools to
help you refine any selection that is currently active. It can save you time, in
fixing problem edges you may have encountered with other selection