I “tie on the needle” like my Mom & Grandma. It goes like this:
Thread needle with long piece of crochet thread. Take a stitch in the block, & go through again.
Take the thread tail & hold up with your free hand, bring the needle around the upper side, making a thread loop & bring needle through the loop. Pull up to tighten.
Repeat (keep tail up with free hand) but this time bring needle around lower (opposite) side, making a thread loop & bring needle through the loop. Pull up to tighten. Cut thread so there are 2 tails. Square knot is done.