To increase accuracy, some woodworkers avoid using the zero end of a rule or tape and use the 1-in. mark instead. You can also use other starting points, such as 2 in. or 3 in. However, when using this technique, you must remember to subtract that number from the actual reading further down the rule.
When installing subfloor plywood it is a good idea to glue it down with a construction adhesive to prevent floor squeaks.