Questions that say I haven't heard a word you said. For example if a guy says he's a doctor and you ask him what he does for a living, it probably won't go over well. You won't make a good impression. Don't worry about what you're going to say next. Concentrate on every word your date is saying. When you do this, your responses will be intelligent and automatic.
Interview questions. Avoid firing off questions one after another. Keep the conversation friendly and fun. Avoid being too serious and look to add a bit of humor if it's naturally part of your personality.
Avoid questions that are too personal. Unless he or she starts talking about things, avoid sensitive questions that might make them feel uncomfortable.
Relationship questions like 'why did you break up with your ex' or 'tell me about your last relationship', ...
Serious discussions about marriage, having children, what you're looking for in a mate, etc.
Political debates and subjects of controversy