Singing is a tried and true method for language acquisition. Popular songs are a good resource for learning current vocabulary and expressions, and children's songs can be used to develop vocabulary and learn new sentence patterns.
The Mandarin song lyrics section of the website has a variety of children's songs. No matter what your age, these songs are useful vocabulary tools. They are simple and repetitive, which makes them ideal for memorizing new words and phrases.
To get you started, here are a few easy ones:
The one disadvantage about singing Mandarin songs is that the tones are not always clear. Therefore, you should first learn the words by themselves - all with the proper tones, before singing the song.