Sometimes bad things happen to good people (lay-offs, health issues, etc.), so credit score is not the only thing to base a decision on, just one of the factors. References are usually weighted very heavily. If you screwed your previous landlord, the chances are much higher that you will screw your next one.
Other than your personal appearance, consider the vehicle you drive. If you show up and fast food bags and garbage are falling out of the doors when you get out, or it looks neglected, that is an indication of how you treat your things.
Have a positivem upbeat attitude. Look yourself in the mirror and try to be somebody that you would trust your property with.