you got a lot more experience than i have, from your statement, and I am self taught for the most part,
to square something cross measure from corner to corner, or the 3, 4, 5 method, one can make a light wood frame 6 foot by 8 foot and 10 foot, for king size square,
when I have built corners, I would snap a heavy chalk line on the footer, that would be the out side of the wall, and figure out which way I wanted the wall blocks to start, set my first corner block, and with a 4 foot level, layout 4 or so blocks, and then the same going the other way, leveling and keeping it straight, one can if wanted use a line for other lines, after the corner blocks are set,
then do the next layer checking with the level to keep it plumb built it up 4 or so rows of block, I usually would then lay that amount of wall and then build another set of corners, take your time and build the corners true and the wall will lay easily, and look good,
my two cents
to square something cross measure from corner to corner, or the 3, 4, 5 method, one can make a light wood frame 6 foot by 8 foot and 10 foot, for king size square,
when I have built corners, I would snap a heavy chalk line on the footer, that would be the out side of the wall, and figure out which way I wanted the wall blocks to start, set my first corner block, and with a 4 foot level, layout 4 or so blocks, and then the same going the other way, leveling and keeping it straight, one can if wanted use a line for other lines, after the corner blocks are set,
then do the next layer checking with the level to keep it plumb built it up 4 or so rows of block, I usually would then lay that amount of wall and then build another set of corners, take your time and build the corners true and the wall will lay easily, and look good,
my two cents
