Contests ...
The thing with contests are
Is it a SINGING contest or a Talent Contest??-- If its a true karaoke contest I would suggest the following criteria
Most important would be
1. (1-10 PTS) VOCAL TONE ( Did they sing the song in key and timing was good)
2. (1-10 PTS VOCAL ABILITY ( Can they hit those high notes ? or low notes of the song)
3 (1-5 pts) Overall stage presence and appearance
4 (1-5 pts ) Attitude
Best TOTAL Score wins ....