I admit when I first learnt to knit I only used one cast on method. I learnt quickly that that wouldn't work for everything and set about learning a few more ways to start my knitting . This post explains a couple of good methods.
The easiest (and the one I started with) is the
wrap cast on. This is done by making the first loop on the left hand needle using a slip knot then wrapping the yarn around your right thumb and slipping this loop onto the left needle, as the second loop. Hopefully the photographs below make this process clear.
This is a great cast on for a nice elastic edge, however it is very difficult to get a neat edge so may not be suitable if you want that perfect hem on a sweater.
A
cable cast on is beautifully neat and is used in a lot of
knitting patterns, so is a great method to learn.
It is started in the same way as the wrap method, by making one loop on the left needle with a slip knot.
The next step is to insert the right needle into this loop, as if you were going to knit the stitch.
Wrap the yarn around the right needle and bring the loop on the right needle through the one on the left needle.
Then slip the loop on the right needle onto the left needle, being careful not to twist it.
To form the third loop insert the right needle in between the two loops on the left needle, as shown in the first photograph below, wrap the yarn around the needle and draw through so that there are two loops on the left needle and one on the right needle.
Slip the stitch on the right needle onto the left, so that there are now three loops on the left needle.

Continue casting on stitches by inserting the needle between the two previous stitches on the left needle.
The cable cast on may be neat, but there is very little elasticity so it is not the best method if you are making something very stretchy such as gloves or socks.