Snapping chalk lines on a log and using hand saws to saw down the chalk lines
Logs are uneven and there are a few things I do to help make the layout chalk line more accurate. I have also read a couple of tips like holding the line down in the middle then snapping twice and using braided spider wire fishing line. I also do this: I hold a combination square with a level bubble while the log is on my work bench on the ends and pencil in a line on each end where I want to start a saw line.