what is the best way to drill mounting holes for tuners on a fender shaped headstock so that all of the tuners are oriented correctly?

Use Forstner bits and a drill press.

Here's what I do. Draw a line from the nut out to the end of the headstock for each string. That line will be on the inside of the tuning peg. Draw a circle the diameter of your pegs. From the center of that circle, measure to the center of the circle for the next peg.
You'll want to get that exact as any variance will be readily apparent. Pay attention to the outside edge of the peg board as well. Make sure everything lines up and is evenly spaced.
Go to sleep.
Check it all again.
Clamp some scrap wood on the back of the headstock so you don't get tear out.
Drill slowly.
There are no second chances here.
You'll do fine.
post your results

Tearout sux!
There are no second chances here..............you'll do fine.
that gave me a nice laugh. That's exactly what goes through my mind during this process. It's either gonna be really good, or really bad.

I use a giant brad point drill bit on the drill press. Works much faster, cleaner and cooler than a forstner bit.

I use 9/16 Brad point bit (dilmar german made, very clean) but still use a block on the bottom side to prevent tearout

i didnt mean the actual peg holes themselves, im more concerned with the screw mounting holes, as i am planning on building a warmoth for my first "build" (i already did a warmoth guitar for a friend, but it came with a template for the tuners) and then hopefully a scratch build or two after that.

Well then you only need to go 1/8 deep at most, those screws are very small, and don't use a very large bit, you want it to grab on some wood.
Good Luck,
Dirk

yeah when i was working on the guitar i would tape the bit i was using to just the size of the screw shaft to use as a reference. any good tips for drilling the screw holes so that all tuners are parallel with each other and are all straight etc?

Sure,
A pencil is your friend to lay it out and a punch to mark the spot to drill. Also you can put the tuners on and crank down the nut if it uses one, look at both sides, then use the punch or drill right through the hole.
Good Luck,
Dirk