I think the C string does tend to stand out, as someone pointed out above it is the fatest string and also while finger-picking you are hitting it with the thumb (the biggest fatest appendage on your hand unless you have some weird hands) I think you can even it out by getting more aggressive with the higher stings when you pick them don't just brush up across them get under them a little and pick up kind of snap them back a little. If you watch some of the old acoustic blues players they really pull on the strings, sometimes you hear them slap back against the frets. I think this sounds great on the ukulele, it really brings out the bright snappy tone of it. Of course this sounds better with more upbeat playing, if you are trying to play slow and pretty this would be a bit much. In that case if you want more balanced sound just play a little softer with the thumb on the C string.