I find the accuracy load from the manual,..and start there. If it says the range is from 60.0gr to 72gr,..but accuracy was best for them at say 67.3gr,..then I start at 67.3gr and go 1gr up,..1gr down, and one set of 5 bullets at 67.3. I then take those 3 sets of 5 rounds to the range, and group them. If I am still getting good groups with the higher charge,..I move up another grain,..until the groups open up, then back down to the previous load that grouped the best,..and work by .1gr increments.
You try to get closer to the target,..and I keep trying to get further away.