Re: What method
I do three stages of load development.
The first involves either research to determine reasonable max and min as-published charge levels for the powder, bullet, and casing; or cautious pressure testing if no such published data is available.
The second stage involves working down from relatively near max (I'd suggest 95% of published max) in relatively broad (I'd suggest 2%) charge increments, to see if any accuracy nodes suggest themselves.
The third stage involves load refinement, experimenting with small charge increments in ranges closely bracketing the suggested node charge levels, and maybe also experimenting with issues like OAL.
Some basic rules apply.
Long experience has shown that max and overmax loads are tempting but neither necessary nor wise. All excesses always carry penalties, they just don't seem so apparent at the time.
When nodes appear at or near max, jumping the bullet is preferable. When loads are comparatively tame, seating into the lands can be considered.
Component substitutions and component lot changes require at least some preliminary load verification before leaping ahead and blindly assuming the load recipe has not been altered subtly and unwisely by the change.
There are no secrets or magic tricks. Nothing is true until proven so, no matter how intuitively 'right' it may feel. Fortune favors the cautious handloader. When in doubt, disassemble the batch and start over; never, ever, leave this step for later.
Greg