Hide the marching ants
My first order of business after making a selection, is to hide those pesky black and white lines. Adobe calls them ‘marching ants’ I believe and I find them distracting when working against a dark background. This can be done by pressing Ctrl+H after a section has been made. Once you are done painting within that selection, you can press Ctrl+H to show it again, or Ctrl+D to deselect everything. Try it!