I recently had a customer who had trouble understanding the cast-on of the Limerick shawl. I wrote up a quick little tutorial, and since many center-out triangular shawls begin this way, I thought it might be helpful to others as a reference.
this particular person had never done a provisional cast-on before, so I tried to simplify things by using a long-tail cast-on. The provisional cast-on makes for the smoothest start, but the Knitting Police will probably not come after you if you use a regular cast-on. When I get a chance, I'll edit this post to add the provisional cast-on step. Here I've cast-on 2 stitches using the long-tail method.
Here I've knit the garter tab, consisting of 14 rows of garter stitch. it wants to twist a little bit in the photo but that’s ok. In the next step, you will be picking up stitches in the garter ridges or bumps on the side of the tab.
Here I've turned the work and knitted 2 stitches and placed a marker. then i rotated the work clockwise so that the long edge of the tab is ready to be worked and picked up 7 stitches (one in each garter ridge) and placed a marker, and then picked-up and knit the 2 stitches from the cast-on. Now you have 11 stitches on the needles and are ready to start the chart. The 2 stitches at each end will be worked in garter stitch throughout the shawl, while the center portion is the lace.
in other similar patterns you may have variations, like 3 garter stitches on each end instead of 2, or a different number of garter stitch rows in the tab. The purpose of this beginning is that you are starting your shawl at the center top edge and working your way outwards by increasing at both ends and in the center of the shawl (the first example here). The garter tab enables you to begin with an edge that blends in with the edging on the rest of the shawl, which is usually maintained in garter stitch throughout. i highly recommend knitting lace triangles as a resource for this type of shawl.