I looked for the scarf pattern for the scarf I uploaded a couple of days ago and this is what I found:
You might find this clearer:
Using 4.5mm straight needles, cast on 44 loosely with DK yarn.
Row 1: Slip1 purlwise, knit to last to stitch, ktbl.
Change to 4mm needles.
Row 2: k2 *yfwd k1, k3, ssk, k1, k2tog, k3, yfwd, k2. Repeat from * to end of row.
Row 3: purl all stitches
Repeat rows 2 and 3 till your scarf is as long as you want it to be.
Change to 4.5mm needles. Knit one row. Cast off loosely.
When knitting scarves, I usually slip purlwise the first stitch of every row and knit into the back of the last stitch of every row. It makes the edges uniform, altho’ I’m not sure it’s any more neat than just knitting (or whatever) the edge stitches. Sometimes it looks better, sometimes it doesn’t; see what you think – it’s easy enough to change edge stitches if you decide to.
The cast on and cast off edges will be slightly at odds with each other – one’s wavier than the other. I suppose if that really bothers you you’d have to knit two halves and sew them together or knit a three needle cast off or something.