That depends on what you're starting with.
I use a primer on the baits I make because I need a sandable "surfacer" to get a nice, smooth surface to start painting on. The raw material doesn't provide a smooth enough surface to immediately start color basecoating on.
You use a primer/surfacer under these conditions because they have a high "solids" content that quickly builds up on the material, and is also sandable - - as opposed to your regular paint, which lays down very thinly and can only be sanded very delicately.
If you're repainting, that smooth surface is usually already there (factory finish), you don't really need primer.
I've never had to prime any of the repaints I've done. Just scuffed and cleaned the existing finish, and took off with my color basecoats. What you might find is that a primer gets coverage much faster than your solid color basecoats.....a lot of guys see enough advantage in this to use a primer just for that reason - - quickly getting a solid color base.
Adhesion promoter is a different animal. You'll hear references to Bulldog Adhesion Promoter a lot. This was designed to help automotive paints adhere to flexible plastic parts (like bumpers).
If you do choose to lay this down, it should be your FIRST coat. It's designed for providing grip to plastic, and that's what it should be sprayed on.
Spray it VERY THINLY. The times I've used it, I've actually sprayed it on the lure and immediately wiped the lure off. Do not apply it in multiple coats.....THIN!!
Then you need to get your paint down shortly after it dries....there is a window for it to work, and after that window, it may actually prove to have the opposite effect it was intended for.
The use of Bulldog is widely talked about in custom auto-paint forums - - it appears to be a decent product as long as it is applied correctly.
I've done lures with it and without it, and haven't had problems either way. I think it's more important to make sure the lure is properly prepped and clean of all oils than it is to use Bulldog or adhesion promoters. It's an added step and expense that I usually don't mess with anymore.