Summarize:

A common length for winter scarves is 60 in (150 cm) because then you can wrap it around your neck multiple times. Keep knitting until the scarf reaches this length, or make it a little longer or shorter if you prefer. Measure the scarf with a soft tape measure once it looks like it is getting close to the desired length. Some patterns will provide an exact number of rows to knit, but with most scarf patterns you can just keep knitting until your scarf is the desired length. in the knit row when the scarf is the desired length. Hold the needle with the stitches on it in your non-dominant hand. Then, knit the first 2 stitches onto the empty needle. Lift the first stitch you knit onto the needle up and over the second stitch, and then knit another new stitch.  Lift the new first stitch up and over the stitch you just knit. Continue to knit 1 and lift 1 up and over until you reach the end of the row. When you finish binding off the last stitch, pull the yarn through to create a loop that is about 3 in (7.6 cm) long. Then, cut the working yarn about 8 in (20 cm) from the last stitch. Tug on the loop to pull the tail of the yarn through it. It’s important to leave at least 10 in (25 cm) of yarn so that you will be able to weave in the end of the yarn. Thread the tail of yarn through the eye of a yarn needle. Insert the yarn needle into the edge of the scarf near the last stitch. Pull the needle and yarn all the way through the stitch. Then, insert the needle through the next stitch going from the other side of the scarf and pull this yarn taut. Repeat until you cannot sew any further. Then, cut the excess yarn about 0.25 in (0.64 cm) from the scarf.
Continue knitting until your scarf measures 60 in (150 cm). Cast off Cut and tie off the final stitch in the row. Weave in the ends using a yarn needle.