Hmmm don't do Take on me by Aha- sounds easy but lung cripplingly hard as I've found to my peril. Beatles songs tend to be fairly easy to do a decent job on. Carpenters also good if your voice is on the lower side. Other ideas - All night long - Lionel Ritchie or Superstar - Jamelia
I am tone deaf (and proud ) and find that confidently butchering a song to the best of my abilities gets me more credit than were I to sing an easy song in a passable way. Always by Bon jovi always works.