An important thing to remember when trying to become a successful cover band is your reputation. This includes your on and off stage public perception. If you have a excellent cover band, the music is tight, and the song selection is off the hook, but your kind of an @ss off stage, your going to run into problems.
Nobody wants to work with someone with an ego. Try to be humble. Your going to find working with promoters, owners, and agents will come much easier if you check your ego at the door. Likewise with set breaks and off stage. You don't want to go to the bar for a drink after a great set, and hit on some guys wife or go outside for a smoke and puff out your chest to a local thats had to much to drink. Use your head and common sense. Be polite.. even if the drunks all swarm you and you find them irritating. Take it as a compliment and invite them to your next show in the area.
Take criticism with a grain of salt. Many times they will have something of relevance to say. Again, these are the people you are playing to.. your fans! If they dont like what they hear then your doing something wrong. On the other hand, don't take it to much to heart either. Analyze the comment, take it for what its worth and adjust accordingly.