You have to be careful when using abrasive products. It's generally best to start with something mild, and if that doesn't work, then move on to something stronger, and then something still stronger until the scratches and imperfections are gone. Then you go back through the same products, using the less abrasive and then least abrasive, to polish over your work.
I use Zymol HD-Cleanse on a routine basis for external paint, tar, and very light scratches. It doesn't contain physical abrasives at all. If that doesn't take care of it, then I use Meguiar's Mirror Glaze #9 Swirl Remover 2.0* as the next step; as a mild abrasive, it's designed to smooth off the microscopic edges of swirl marks resulting from improper detailing (dirty rags, overaggressive use of a buffer, etc). It's mild enough that it leaves the finish smooth and shiny. If any paint or scratches remain, I then go to Meguiar's Mirror Glaze #2 Fine Cut Cleaner*, which is slightly more abrasive and might also smooth over any scratches, but you'd want to go back over the area with the #9 afterwards. Once you're all done with these products, it's a good idea to put a coat of wax over the finish.
*Meguiar's labels its products on a scale for how abrasive they are, from 0 = light cut to 10 = heavy cut. The #9 is labeled as 3, and the #2 is labeled as 5.