Danielle has a great reminder for how to make your cast on and bind off match every time! This technique is wonderful, especially for scarves and baby blankets, so your project is symmetrical. Use a provisional cast on at the beginning so that after you bind off your project, you can tear out the waste yarn and pretend your starting edge is a bind off edge! Using a Provisional Crochet Cast On makes this easy.
You can find the Provisional Crochet Cast On, along with tons of other great cast ons and bind offs in the book Cast On, Bind Off by Leslie Ann Bestor.