I only have a few things to contribute to this. I agree about not using the promoter: A.) it isn't necessary at all if you do the prep work properly, and B.) it is just one of those additional products that people try to tack on to other products they sell to make more money.
Solvents like paint thinner and dewax work, but they can leave residue. My recommendation is to first wash your parts in the sink like dishes using Dawn dish soap. If they aren't new and came off a car, they are not only dirty anyway, but the Dawn removes grease and oil and wax very very well. The next prep step is to use 95% isopropyl alcohol and clean white cloth from old t-shirts to wipe them down thoroughly...and use Q-tips dipped in the alcohol to get in crevices and hard to reach spots.
Alcohol is not only really cheap, but it is a great solvent for water based and oil based residues...and it evaporates clean, meaning it leaves no residue of its own.
SEM also sells a wide range of colors that do not come in a spray can. They can also color match and make custom colors. Preval sprayers are little compressed air spray canisters that screw onto a bottle that you put the paint in. The spray produced is even finer than what you get in any spray can, and both the kits and additional canisters are extremely cheap.