Funny, I recently posted a thread about the same issue. It seems the paint chip kits disappoint, the better option is to get touch up paint from MB (colour match reported to be excellent). You apply light thin coats to build up a layer of paint up to the point where your chip is filled with paint, with just a little bit of overlap around the surrounding painted surface (to blend in). You use light grade wet sandpaper (1000 and up) to level the surface, and then use paint polish compounds to get your gloss finish back and this should blend in nicely. There are tutorials for this on the web. I've done it in the past and short of a complete respray, it is the only method I've tried that can give me the result I expect (no less than near-perfection).
It takes patience to do it right, but it does not require ninja skills. Possible pitfalls: lay the paint too thick instead of multiple (5+) thin coats. If you lay it too thick, the surface hardens, but the lower portion of your thick layer will take weeks -if not months- to dry, and you will get undesirable wrinkles in your finish.
Good luck!
Jerome
