Where I worked it was 12 blades on the starter - prime for three blades- wait 3 blades then repeat. This was to ensure there was no hydraulic lock.
After 12 blades magnetos on and then prime as needed until the engine fired then mixture to auto lean.
Each engine was different - some started very easily others required switching between the primer and mixture controls to get them running.
If the engine was cold I wouldn't do anything with the primer - just put the mixture straight to auto lean. That worked very nicely.
The above is for the Pratt and Whitney R-1830-92.
I would start the right engine standing between the seats so I could see what was going on. Right hand for the starter left hand for everything else.
Left hand engine started sitting in the left seat - same use of hands.
I've even started one engine with a rope wrapped around the prop dome and attached to a pickup truck - works too!
I've heard it's possible to hand prop large radials - the technique has been explained to me but I've never seen it done.