"The producer advertised two songs for around 400.00 but when I informed him there was no wrtten music thats when he starting talking 50-50"

The plus side of that is the producer may have a personal interest in the promotion of the song if he shares the copyright. Also, he may work harder at the music if a slice of royalties could be his in the future.

Read any agreement carefully (many variations). I've hired several singers in the past. Though they were paid well up front, in the agreement, if I made over X amount ($2,500 I think) on the track, they were entitled to another payment of $500 - $750.

Good luck, John smile