Well depending on the medium you intend as final you could reduce the size of all the labels. You could also use different fonts (but for some reason people here tend to take issue with that, even though it works and has been common practice in mapmaking for a long time), for instance the fancy one you got on the big labels and something simpler on the smaller city labels. I wouldn't use different colours on the labels, but I think using different saturations of the same colour could be used to help distinguish them from one another.