Summarize the following:
If you want a lacy effect that will also help the scarf lay flat, add 6 stitches to your scarf when you cast on. Knit the first stitch, wrap the yarn around your needle and use it to knit the next 2 stitches together. Work the pattern across the row until you get to the last 3 stitches. Then K2, yarn over, and K1. For the following row, purl the first 3 stitches before you work the scarf pattern and purl the last 3 stitches.Repeat this for the rest of the scarf to create lace-like gaps for the border. You can add a few stitches to both ends of your scarf to prevent curling without creating the look of a noticeable border. For one of the simplest selvedges, cast on 4 stitches more than what your pattern calls for. Knit the first 2 stitches of every row and then work the pattern as directed. When you get to the last 2 stitches, knit each of them. Repeat this for every row of your scarf to make a double garter selvedge edge.
Make a decorative lacy border. Knit a selvedge if you don't want a large border.