Like Gunwizard, I use a black square and aim at one of the corners. Usually I use a Leupold sighting-in target. It givers me 4 targets per sheet. "Aim small, hit small." The corner of the squiare with the vertical crosshair bumping the right side(for ME) and the horizontal touching the bottom allows me to be sure I'm aiming at the infantismally-small aimpoint.
If I am working up a load, I use a 20x scope on the rifle of choice, then after choosing a load, installing a "hunting" scope appropriate for the rifle, ie a Redfield 2x-7x Widefield in my .270AI.
Several of my rifles use Lee dot-equipped scopes...whereupon I use a hand-made target with black dots for aiming points. If I'm using a scope with a, for instance, 4moa dot, I put some 4" circles (for 100yd or 8" for 200yd) so the dot and the circle are the same. The bullet lands wherever I need it to in relation to the aimpoint. If I need it to land 2 1/2 higher than the aimpoint...so be it. I'll be sighted in when it does so.
I've also made some targets that have black squares and several different-sized circles so I can shoot a couple different rifles at the same target before I go up to change it.
Yes, I don't shoot at a public range.
Have fun,
Gene