i think the mostly used short-cuts for me is:
Ctrl Z/X/C/V (undo/cut/copy/paste, use them alot in different
areas.mostly documents and picture editing.)
Alt F4(The fastest way to exit games,doesnt work on some games
though.)
Ctrl P(faster than clicking print button)
Crtl A(select All when managing files)
shift/ctrl while drag and drop(When i drag and drop, i use
shift/crtl to force it to move/copy, cos by default, when you drag
a file within the same drive, it's move, when it's another drive,
it's copy by default.)
Ctrl F(Find, mostly use it when looking for something in within a
webpage/document)
Shift Enter on "my computer"(I like to use "explorer" to
browese/manage files instead of "my computer", but most ppl dun
have the file explorer shortcut in desktop, so i just shift-enter
on the "my computer", it will be in file explorer mode).
Alt Tab(switch between applications, use it alot.)
Right click S ---> Alt S(use it for surfing porn, hehe. open the
pic, right click it and press s, the save window come out, and then
press alt-S to save it.)