⦁ Too many songs– Demo means demonstration. The record company wants to know what you can do, they don't need to see it all. You don't need to hear every song in a musician's repertoire to know if they are good or not, so don't send everything – it makes you look unprofessional.
⦁ Starting with your weakest track – Some artists think that starting with their weakest track and building to the finally will make them sound good, but it doesn't. You best track should always be your first. Wow in the first few minutes and they won't forget it. Bore them, and they won't listen long enough to hear your best.
⦁ Unprofessional editing – It is super easy to mix and master your music these days, and a sure-fire way to show record labels that you are an amateur, is to not master your own music. They will accept imperfection, but they will not accept laziness.
⦁ Apologizing – Labels want you to get to the point. They don't want a sob story, they don't want to hear that you are sorry for being bad, for being unpolished, for anything! Be confident in your abilities and only say what you need to say.
⦁ Mass Sending – Another mistake too often made is to mass send your demo to every record label you have ever heard of. You should be choosing your labels wisely, based on who you think would best suit your music. This can make you seem desperate.
⦁ Sending CD's or Tapes – Don't send chunky retro junk. The best way to send your music is using SoundCloud. This way, the label doesn't have to download and delete, and they can see how popular your music is if you already have a following.
⦁ Saying too much – Mystery sells. They don't need your life story and they don't need any details on why you wrote every song either. Let the music speak for itself.