Long-tail cast on
A great all purpose cast on as it offers some elasticity.
M1L and M1R increases
These increases are commonly used when working top down sweaters, though there are many different ways to work increases in knitting.
Backwards Loop Cast On
This cast on is typically used when adding stitches onto the ends of a row. For example, when knitting a top down cardigan, you may cast on for button bands after working some neck shaping. It can also be used when creating buttonholes.