Religion:

Talks of faith, especially when they're opposing thoughts can be down right disrespectful, even if you're the most eloquent person on the planet.

You may want to make a joke about Catholic priests and little do you know, your business partner is Catholic.

Avoid religious talk because people place their entire belief system on their religions.

Also, just because you're not discussing your beliefs doesn't mean that you don't have them.

 

Age:

Never get yourself into the 'guess-my-age' game, especially if your business partner is a woman. Avoid asking about people's age or any comments relating to it, e. g. something as innocent as this:

'You look much better than other women of your age.'

 

Politics:

Personal opinions on politics is just one of those things that always riles people up and why would you want to cause that kind of ruckus having a business meal or starting an important business meeting? Politics are always opposing opinions and having that type of intense discussion is only going to lead to anger towards the people you want to have a good rapport with.