If you treat your existing customers well, they'll do your bidding for you. New users are important - but if you treat your existing users well, they'll go out

If you treat your existing customers well, they'll do your bidding for you. New users are important - but if you treat your existing users well, they'll go out of their way to tell other people how great you are. I think the most effective type of marketing will always be the personal recommendation from a current user.