I make 10 rounds for each powder weight I want to try. I shoot 5 @ 50 yards and 5 @ 100 yards. (50 yards is to make sure my scope is on with these loads).
I start at the recommended start weight and work up loads in .5gr increments to see what groups best then work in smaller amounts around it.
For instance: if the start weight were 26gr and top load is 30gr I would load 10 each at 26, 26.5, 27, 27.5, 28, 28.5, 29, 29.5, & 30. If 28.5 and 29 look similarly promising I would then load 10 each working away in both directions in .2 or .3gr increments until I found what I liked. So, I may load 28.3, 28.7, 29.2.
This is part of the fun of reloading--you get to keep trying combinations until you find what you like!
Hope this helps.