I imagine all vertical rows to be warps and all horizontal rows to be 2 wefts (2 picks). That means that one black square represents the crossing of 2 weft yarns (2 picks) over one warp.
I ensure that the strips are pushed down as far as possible (they will not move further down when I start beating the weft down) and that both strips are at perfect right angles to the warp ( at 45% .)
It is never a good idea to weave tapestry over the entire width as the weft would pull the warps too tightly together. I divide my strip into sections about 10 cm ( 4" ) wide. I start on the inside of the first section, so that the end of my weft yarn will not hang out at the selvedge. After every row (2 picks) -one weft towards the egde of the tapestry and one weft back to where I started) I miss one warp. When I start the next section, I overlap the second section one warp over the first section in every row. Repeat to the other edge of the tapestry. I tuck the weft ends to the back of the tapestry, leaving ends 5 cm (2")long.
