You can use some Keyboard Shortcuts for minimizing Windows:
Mimimize all Windows: Win+D or Win+M
Minimize only the active Window: Alt+Space+N
BTW, i never minimizing windows, i let them always open and change between them with Alt+Tab, Alt+Shift+Tab (Tab can be pressed more than one time to jump to the next Window in this Last used priototy List), The Taskbar and a Special Function of 7+ Taskbar Tweaker.