Cripes,
I don't know if the "tips first" method makes for a better final product, but I find it a little easier to shoot the yellow over flat white rather than having to cover the black blade paint later. Painting early USN props with the multi-color tips is definitely easier by doing the tips first. Honestly, it's just builder preference, I used to paint the tips last and just found I got a better result doing them first. Masking the tips is very easy and quick, especially helpful when you build as many B-17s, '24s, and '29s as I have. Heck, I used to dip the tips in yellow paint and carefully wicked the excess off, and that worked pretty good!

I think you'll like tips-first if you try it.
Oh, on the subject of weathering with salt--that seems to be a great method, though I haven't ever tried it. The results look pretty convincing, especially in 1/48th scale and larger. I've done chipped panels by using dried-out Metalizer and the drybrush method with good results.
Scott