If you're not using keyboard shortcuts and tricks, you are wasting precious time that could be better spent on YouTube. Here's a couple of my most used keyboard shortcuts for the mac.
Safari Specific shortcuts
to switch between tabs in Safari
to jump to the search field in Safari
command and '+' or '-' to change the size of text in Safari
Hold down the ctrl key while scrolling the wheel/ball on your mouse to zoom your display in and out (I wish my PC had this)
to lookup a word in the built in dictionary
cmd and tab to bring up the application switcher