A problem with getting repairs to match is that not only must the color match but the manner of application must be the same also. Otherwise the way the pigments are laid down will be different and the repair will be noticeable. Even spraying, for example, must be done in a substantially same way (gun settings, paint thinning, application thickness) or it will not match. This is why entire panels are done as rhenning mentions; spot repairs will never blend properly.
Just do the best you can and look at them as war wounds or as blemishes on fine leather or a beautiful woman; signs of character and distinction. I mean, it's a bike, it's going to get blemishes unless you hang it on your wall and don't use it.