I am thinking "melodic" might be one of them, but there are probably many words, because melody is only one aspect of musical conventions, so please tell me if you know one, and also I think there's a word to qualify something that conforms to all conventions, or some of them, but I have no idea what it might be. I think conventional is too general and doesn't really pertain to music specifically.
For example:
Her musical composition was ____.