my best advice: Don't Give Up!

we all make mistakes at certain points. with scale modelling, you learn by experience. I have only 3 completed models under my belt, but when i look at them on my shelf every day i could see the progress I've made on each one, and with the models I'm building now I'm more keen on the little details of building, painting, and weathering.

ok, from your post i could see you are doing something good, starting with cheap kits. to me thats a perfect way to start, if you mess up, so be it, its good practice anyways! ;D

from your description, i can only assume that you were trying to go for a too heavy coat of primer in one shot. spray can primers need a little getting used to, there is a certain distance you should be from the part and you should spray in very thin misting coats and gradually build it up to prevent detail loss. try spraying a scrap piece and practice building up light coats of primer.

next, what kind of paint are you using? some paint (such as Tamiya) are notoriously difficult to hand brush while others (like Vallejo) hand brush perfectly. its a matter of experimentation to find the right thinning ratio for hand brushing and i recommend painting a test piece (scrap parts, bottles, etc.) and practice. and make sure you have good brushes as well!

i really hope you dont give up scale modelling, its a very rewarding and fun hobby in the end, its just a matter of practice, practice, and more practice! ;D