Hi Cassie. I'm not a songwriter, but I LISTEN.

AS someone above said, a song can't be too simple. Good songs tend to be simple. Great songs are memorable. Some times the music/tune hits them, and other times, the words. Occasionaly, it's the story the song is telling. Believe me, a good song will have a story to tell.

Now, about rhyme. It is a tricky thing. Sometimes a clever rhyme can be the hook for the audience. However, those above who said it, rhythm is the king. The song which sticks is going to have a strong rhythm that the words can easily align with. You can craft a song with a marvelous tune, and wonderful words, but if it can't maintain its internal rhythm, very few people will sing it. The singer would know it, but if the audience can't follow it musically it's not going to provoke them enough to sing it.

Some people write all the time. Lyrics don't have to rhyme, but it's easier on the audience if you do.