The first step is to cast on 30 stitches (or half a mitred square's worth) I personally like using my favorite long tail cast on.
Place a marker and beginning at the base of the first square begin picking up along the edge.
Pick up 30 stitches or 1/2 a square's worth. The last stitch should be right in the corner of the opposit end of the square.
Turn work and knit back. Working the decrease rows on right side of square and knitting back on wrong side, as directed in previous post.
We will discuss the next square soon!