My Technique
Initially (early empennage parts), I did the full Alumiprep/Alodine stuff before priming. I recall reading a recommendation purported to be from an AKZO rep that said just to wet abrade with Scotchbrite, then, when dry, wipe down with acetone to remove any remaining residue and then shoot the primer. This is basically the process I have followed on the rest of the plane:
1. Using gloves, I scrub the parts wet with a #7447 (maroon) Scotchbrite pad. Usually, I set up a plastic folding table outside and use a hose to keep the parts wet and rinsed.
2. Still with gloves, I wash the parts with a green Scotchbrite and Dawn dish washing liquid to remove most of the gray residue and any oil/grease from the parts. (The gloves are to protect the parts from me - not the other way around).
3. I let the parts air dry. Then just before priming (always within just a few hours of the wet abrading), I wipe the parts down with acetone (using gloves - obviously). I typically use Scott paper towels/rags in the pull out box. I keep wiping the parts down until the wipes quit coming up with gray residue.
4. Shoot the parts with primer.
I actually shoot the primer indoors. Early in the build, I built a "painting table" that is basically 6' x 3-1/2' wire grid surface over a baffled box with a filter and fan pulling air down through the grid surface. This takes care of controlling most of the over spray. I also have a 24" industrial ventilation fan and exhaust vent built into the wall that takes care of any fumes. As a result, I can actually shoot the primer without any respirator (except when I have to shoot larger parts that don't fit on the painting table).
In my experience, this process yields better results than my previous method. The primer seems to adhere much better than it did to the Alodined surface. After it has fully cured, it is virtually bulletproof. I have yet to find a solvent that will touch it and it is very scratch resistant.
YMMV