I have yet to find one of the commercial hype kits that works.
By accident I stumbled onto this. I use the standard factory repair paint tube and carefully put paint into the scratch and immediatly use a stiff and very square (as in nice crisp edges) medium soft plastic tool to plane off the excess paint. Do this in really cool place. The idea is to deposit paint only in the sratch and then to remove all of the excess that is sitting on the paint next to the scratch. Once everytyhing sets you can wax it in of buff it out...