Not really. Missing something. You discover as you go on.
A selection is the opposite of a mask.
selection: do something on the area I selected
mask: do something, but not on what I masked.
quickmask can be handy for making switching between selections and masks. The mask can be seen, a selection only shows marching ants, and when there is partial transparancy, you can guess what your selection covers as the ants show 50% opaque/transparant.
Suppose you have to make a perfect selection of a wine-glass with shadow on a whithe cloth. You can start with dragging a selection that is a bit too large, and then with soft brushes, you paint on the mask, making the brushes smaller and smaller as you go on.
You can change the colour of the rubylith, you can invert the mask, and you can paint with the opposite colour to correct when you were you couldn't walk the line.
much fun in there.
but don't forget to save'em.
personally, I proceed as said: a rough selection (when you start with a QM from nothing, PS can act bizarre) and then masking.