I use the primer at walmart and it holds up pretty good but I mostly paint anime figures and transformers so I never tried it on other ones but its about .99 so its worth testing on a junk figure.
what you want to do is try and only prime the main areas of the figure. getting primer on the joints will chip easily. go out and buy some Sharpie Paint pens, you can buy them in lots online for made cheap, otherwise they are 5 bucks each in store (7 up here in canada). Paint the joints with these non abrasion markers, then prime but do light coats. but don't waste ur day doing tiny b!tch coats lol. but like buddy says, you don't always have to prime, some of my best figures I didn't prime. so try out different things. make sure you get a good primer, but even cheaper primer is awesome, and will dry in less than 5 mins (Don't GO CHEAPER THAN KRYLON) lol
I usually don't thin it when I do use it,but a lot of the time I don't prime figures at all,I just throw an extra coat of paint or so on it instead,I would try testing it out a couple different ways on a crappy test figure,see what you like best,good luck!hope it helps