First off, Welcome!
You don't say if you are using a machine for the polishing, so I will respond as if you are working by hand. The rubbing compound should be fairly aggressive, so using a finishing polish to refine the paint more is always a good plan. Think of it like sandpaper in woodworking - start with a low number grit to remove the 'big' stuff, then finish with a higher number grit to smooth out the surface.
If you will do more cars in the future, you should look into polishing with a machine - it is much faster and produces better results. A random orbital, dual action machine (Porter Cable, Adam's Swirl Killers, etc.) is fairly simple to learn to use, and if you are mindful with the operation of them the only way they will damage the paint is if you drop them on the car!