Paint Question

I have a 79 Cordoba and wanted to touch up a few areas on the car myself while I can hopefully save for that future paint job. The areas I'm looking to touch up is the bottom of the rockers; below the stainless trim and I'm looking to touch up the inside bottom of the doors. My car was last painted in 1998 but, these areas were either sprayed thin or not touched at all.

So, here's my question. Do I just scuff up these areas and use a matching touch-up paint in an spray-can. Kind in mind these are areas that are typically seen but, I'm just trying to protect things temporary. It is my understanding that Maaco kind of does this same thing with their cheaper paint jobs? I've heard they don't even use primer. Just scuff and shoot with a cheaper paint?

Just curious if I should use primer or base/clear? I've never done this before as I'm younger but, looking to kind of learn some of the basic stuff. Sorry, for the amateur question here. Thank you in advance.

What kind of paint was it painted with before? If you're doing this as a temp thing with a spray bomb, yeah, you can do it this way but it will probably not last all that long. I kinda used my 95 Dakota as a test bed for doing stuff like that and even tho the spray bomb stuff stays on ok, it usually fades fairly fast. If the car is white, it'll look ok for a longer period but the darker the color, the faster it fades. The white fades just as fast but it's not as noticeable.

We used to do this when I was a teen and didn't have the correct equipment. It will work as a stop gap measure but as Cranky stated it doesn't last as long as a pro job. Here is a link to a touch up paint site. Good luck.
http://www.automotivetouchup.com/

Thank you. I'm just paint the very bottom of the rockers and fenders. It's that typical area that doesn't get enough paint. I'm assuming it resprayed in the old enamel.