Stay in the moment, my young Padawan.
Great tips Oz. (Being a member of the Local Starwars Fanclub, I will be at the first viewing here in Antwerp, surrounded by Chewys, Darth Vaders, Emperors, Darth Mauls and hopefully an Amidala who will look into my eyes to see her own beauty reflected).
My tip, the first that comes to mind: sometimes you need the rectangular or other selection tools, like for example for cropping. And often your selection doesn't start exactly where you want it to. But if you drag while holding down the space-bar, you can move your selection without changing its size. Let go of the spacecake err -bar and you can continue drawing your selection.