Here are various methods of casting off your knitting.  Some are more flexible than others, and some are more "decorative" than others.  The Knitted Bind Off has two videos showing slightly different methods.  This bind off is a little stiffer than others, which makes it good for the shoulder seam at the top of a sweater where it contributes to the "seam" construction and gives your sweater a little more structure.  BingBing's cast off is delightful and was new to me.  It results in a very stretchy bind off with a decorative beaded edge.

I will post more as I find clear videos of interesting cast offs.  Learn them all, adding them to your knitting tool kit, so that you have choices.  And check out the videos on Casting On as well....the more you know the better off you are.