I noticed in Hershel Houses (or it might have been Jim Turpins) video that there was a level built into the drill.
So, for either pilot holes or pin holes where I could get the right bit into my Dremel Tool I noticed that there was a flat surface on the tool itself parallel to the bit. I glued a plumbers level there and it works well for pin and lock bolts once you can ascertain the top barrel flat is set in the vice so that it, too, is level. That eliminated the need to eyeball because all I have to watch is the horizontal 90 degrees.
I've pretty much hit my plateau in terms of skill or talent, so I haven't looked beyond this. The only time I'll use my drill press is when , say, a stock comes with flat sides or lock panels.
The other element to this that is always present is having a really good eye. I don't, so I don't dare try anything I can avoid that requires such if I can measure or set the tool or piece. Out of cold fear I will check two or three times before working.
When I was a junior member here I said what I will always say...there's a reason Cordwainers make shoes and riflemakers make rifles. My heels are always level.