I tried knitting a lengthwise scarf a while ago, but I ran into a few problems when casting on and binding off; my cast on was too loose and my bind off was too tight, and the scarf did not turn out properly.
Any recommendations for the proper cast on and bind off techniques for the most even tension?
If you used a backwards loop cast on, try doing the long tail, instead. The rule of thumb for how much yarn to allow for in the tail, is about an inch for each stitch you’re going to cast on if the needles are a medium size (maybe US size 4 - 10) and a 1/2" per st if smaller needles, and 1.5" if larger.
As for the bind off-- that’s a common problem. Just do it very, very loosely. You can see how it’s going as you bind off, so if it’s too tight, rip it back and start it again. Try using much larger needles than the ones you used for the scarf, that can help.
I second a longtail or cable cast on, they provide a firm edge, even when done loosely. For the bind off, use a needle about 2-3 sizes larger than you knit the scarf with.