Row 1 and every odd numbered row: K2, purl to last 2 stitches, k2.
Row 2: K6, *yo, ssk, k1, (k2tog, yo) 2 times, k3, repeat from * to last 2 stitches, k2.
The number of sts per row stays the same. When you look at the row, each yo is paired with a ssk so that every time you add a st with a yo, you decrease one st with the ssk or k2tog. I think that markers between the 10st repeats might help keep track of your sts. That way it'll be easy to see where you may have forgotten a yo or a decrease.
Sometimes getting started with these patterns is the most dificult part. After that you can see the pattern and follow the previous rows.
This looks very pretty. Good luck witlh it!