To start with I'm an antique and use old methods. In the search for the ultra small group here is where I start.

With the cases, fireformed. Trim all the same length even if it means under minimum. That squares the cases mouth for any cartridge, this is very important for leverguns with a bullet to be seated with a crimp groove. This is especially true when shooting them short large dia pistol bullets in a .44 or .444 aka under 240gn. Then neck turn for precision bottle neck rounds. Straight walled cases are tapered from one end to the other so outside neck turning is an iffy thing to do. But you can check the neck wall thickness with a ball mike and cull any bad ones. If you have a locking ring on your shell holder remove it and use a small pony tail rubberband to hold it loosely. Neck size in a neck sizer die that has been bottom out against the shell holder with a little spring back to square it to the press and die mated and to push it to the center of the threads. Lock the ring, with the press down and a slight load on it. If a bottle neck case do the same with the seater die with a precision ground piece of stock to allow the crimp to be by passed. This squares your seater. Same with straight walled but you have to crimp afterwards. The 120 degree turns do it if it is necessary by checking. Once your dies are set up it usually is not necessary. Kind of like having a Redding Master measure and loading ball powder, no need for weighing once you get your load set and the setting recorded throw a couple and load the rest. The vee block method is a good precision method to check. I have a mandrel style that holds the bullet and casehead with an indicator in between. Easy method roll it across a table watching the bullet for wobble. All the above is just to seat bullets straight and square. Easy once you get used to doing it. My case prep for hunting rounds goes much farther as I try to give my quarry a one shot kill. With them I drill and deburr the flash holes, sorting cases etc. Being in my prime geezerhood I try to get every edge I can anyway.

After all this is done I consider my load testing scope 8-40 power on 40X with an 1/8th minute dot to be the best edge I can have when load developing. If I can hold it still I use a notebook reinforcement pasted to a piece of cardboard aiming at that 1/4 inch hole at 100 and holding it inside that hole does take the "did I pull it" out of the equation. I guess I'm rambling now, hope I've helped. Bottom line I have shot in the low .2s at 200 when using that method with .222s, .243s and one .257 Roberts. Not bad for using a press. Never did care for using the hand dies though I did for a few years.