Lots of patterns use a provisional cast on. Going back, picking up stitches and working in the opposite direction is a skill all knitters need to have in their arsenal.
Here’s my favorite way to do this cast on – using a crochet hook.
Step 1: Get a smooth yarn in a contrasting color (this one is red) from your main yarn. You want it to be smooth so it’s easy to pull out later, and you want it contrasting so you can tell which is the yarn to remove.
Step 2: Point you needle to the right. You only need one knitting needle for this.
Step 3: Make a slip knot with your scrap yarn and slip it on the needle. Make it a bit looser than normal. First stitch cast on.
Step 4: Place your hook under the needle, to the right of the st(s) on the needle.
Step 5: Wind the yarn under the hook and counter-clockwise around the needle.
Step 6: Pull the yarn through with your crochet hook. Again, pull it slightly looser than normal. One stitch cast on.
Repeat Steps 4 through 6 until all stitches are on your needle. In this pic we have 10 sts cast on. The remaining loop on the hook DOES NOT COUNT.
Once you’ve cast on all the stitches, you’ll have one loop still on your hook. Make a few chains in the yarn (not on the needle) and then cut the yarn and pull through the loop.
You’re done! Start knitting with your working yarn. Here it is after a few rows were worked.