First, forget about stand over. Don't stand over. Ride.

Next, realize your static point: crankset. Doesn't move.
Next, reaching the bars comfortably, and this is top tube length.
That determines your useable frame size.

After that, fore and aft are: stem length (most important), seat post setback, saddle position (tweak).
After that, height rear is seat post length; height front is stem rise. Both tweaks.

I stick to these points consistently, remembering three basics:

1. Look down and see the front hub. (top tube length, stem reach, seat post setback, saddle position). The remaining variable here is bar reach, C&V bars don't help much here.

2. Arms flexed/bent a bit in both the drops and on the hoods. (top tube length, stem reach, seat post setback, saddle position). You see the pattern by now...

3. Legs nearly extended, but not quite, at the bottom of the pedal stroke. Seat post height and to a little extent, crank arm length.

All sizing is trial and error, but you can really narrow it down by getting a fit done at a shop that is not going to sell you a bike. There are also "sets" of measurements out there that you can do and apply charts. Always have two people measure you at least twice, and take the average.

There are also types of fits, from relaxed and more upright (that is getting more and more popular), to the Merckx fit that stretches you out.

So, start with the right top tube length for you and go from there. Simple, huh?I