It's worth learning to crochet a simple square.
Click Here for Free Granny Square Scarf Pattern
You can then crochet a square any time you have some oddments of wool after completing another project.
You can choose any size crochet hook and any ply wool.
When you've made sufficient squares to make a scarf of your chosen width and length sew the squares together and add a fringe if you want one.
They are popular and make attractive gifts and they are inclined to draw people to your table if you're having a stall.
These scarves were crocheted using a 4.5mm hook and 8 ply wool (double knitting).
Once you become proficient you'll find that crochet is generally quicker than knitting