How do you keep stockinette stitch even?
Try holding your needles close together when you work, work right at the tips of your needles, and not pulling your yarn too tight. It’ll help your stitch slip easily and smoothly over the barrel of your needle. With practice, your knitting may feel smoother, resulting in more even stitches.
How do you fix curled edges in knitting?
Spray a linen towel or dishcloth with water until it is quite damp, and lay the towel on top of the scarf. Then press the fabric with a steam iron on a high setting (never press directly onto a knitted piece with a hot iron). The heat and steam will stretch the yarn somewhat, relaxing the tension that leads to curling.