[snuffy]

There's as many different proceedures that reloaders have for load developement as there are different calibers!

That said, here's how I do it.
1. I select a bullet for the intended purpose.
2. I select a powder, I may already have it, I may select one I don't have.
3. If the load is for target use, where I can single load, then seating depth can be anywhere from touching the lands to max OAL in the manual. If the load is for hunting, mag length is what controls the max OAL for THIS load.
4. I start generally a grain or 2 over the suggested minimum, a middle load. The lowest load, the suggested minimum is usually 10% less than maximum. Seldom does the suggested minimum shoot well. So eliminating it saves components. I then pick a .5 or 1.0 grain increment to arrive at maximum, usually 5 load levels. Whether .5 or 1.0 depends on the capacity of the case, .223, I might do only one quarter grain increments. I usually load 5 rounds per increment, but in magnum calibers, or with expensive premium bullets I load 3 rounds/load.
5. As far as primers go, choose one and be satisfied with it. Switching primers means you have to start load developement over. Especially if your load is near the maximum.
6. Testing should be on a calm day with no rain. Be sure you have a firm rest and a solid bench. Targets are important, you need to be able to see the bullseye or aiming point clearly. I never test under 100 yds with a scoped rifle. it's a waste of ammo to test at 50 yards, the bullet may not be completely stabilized at 50 yds. If you get a tight group at 100 yds, then it's time to back up some. 200, 300 yds. will tell you if the 100 yd. group was a fluke!