Don’t talk bad about others.
In business (and life) there will be countless times when you are in competition with someone. Never talk bad about those you are competing with, or what they represent. This will only make YOU look bad.
There will even be times when you are not in direct competition with someone, where you will be tempted to speak in a way that put the other party in a poor light as a means to demonstrate how good YOU are. This will make you look bad as well.
You should never have to tear down something else to make you look bigger….you always look bigger when you let who you are and what you stand for speak for itself.