If you've been using a Mac for a while, you probably figured out already that Cmd + M minimizes the foreground window. But, whenever you want it back, you've always had to rely on the mouse.

The app switcher on the Mac allows you to maximize (or un-minimize, if you want) without using the mouse, and it's quite simple actually: 

1. hit Cmd + Tab to bring up the app switcher;

2. cycle through the apps with the Tab key and pick the one you want;

3. and then, before releasing the Cmd key, hold Option (Alt) down and the minimized window will come up.

This works with apps without any windows opened too. In this case, a new window will be opened.

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If you're a switcher, you've probably noticed that Macs don't handle windows like Windows do and that the feature you miss more is that maximize button that resizes the window to match the whole screen (by default, the maximize button on windows [on the Mac] resizes the window to match it's content, and toggles between this size and the original size).

Well, OS X can do it too and, again, is pretty simple: just hold Shift while you click on the green + (plus) button on the top left corner of each window.

Hope this will help to improve your experience with OS X.

-João