The long tail cast-on gives a nice stretchy edge. This is especially useful for hats and sweaters, which need to expand when you put them on. It is also just a good basic cast on, so we use it for almost everything we make, even non-clothing items.
You'll need...
Yarn
Knitting needle
Here's what to do...
Hold your yarn about 6 inches from the end - those 6 inches are your tail. Using the side of the yarn leading to the yarn ball, wrap the yarn around the needle as many times as the number of stitches you want to cast on. So if your pattern calls for 20 stitches, wrap the yarn around the needle 20 times.
With the hand that was wrapping the yarn, take the yarn back off the needle holding to yarn at the point where you stopped wrapping. Make a slip knot at the point in the yarn where you have removed it from the needles. Put the slip knot on the needle, with the tail facing you and the working yarn (which leads to the yarn ball) facing away from you.
Hold the needle horizontally so that the yarn hangs down vertically. With your opposite hand, grab the hanging yarn, then put your thumb and index finger between the two strands, while still holding the yarn with your other fingers.
Open the two fingers to create a diamond. The top of the diamond will be your needle, the sides will be your index finger and thumb, and the bottom will be the rest of your fingers.
Move the needle down so that you are making a v-shape with the yarn. Now you are ready to cast on. Steps 6-9 are the pattern for one stitch.
Move the point of the needle down and to the left, then bring it up and through the thumb loop
Move the needle up and over the right loop (index finger) then turn it back to the left and down through the index finger loop.
Continue to the left and all the way back through the thumb loop again and out.
Drop the thumb loop and gently tighten the stitch on the needle
Repeat for as many stitches as you need to cast on.
Recipe by blossomsandposies.com at https://blossomsandposies.com/blog/basic-knitting-long-tail-cast-on/