Anybody who has taken one of my consulting skills sessions knows how much importance I place on the warm-up. In any interchange between people, I believe that everybody must get psychologically get in contact before business can be done. The approach I find that is effective is to find some subject that is relevant to the subject of the meeting that is not controversial and have people share briefly on the subject.
Many people use the weather but I find that is OK but other things are better. If you know of some new announcement that the industry or company made, you could talk about that. For example, "You must be really pleased how well product X is doing in the market" or "What do you think of the latest announcement of Microsoft?" (Assuming the person knows about it.) "What do you think about X?" is always is a good one.
Avoid, at all cost ,controversial or items that might evoke negative reactions.
In one on one meetings, use something that you both have in common.
Another important point, if a meeting is interrupted by a phone call, coffee break, or something else, remember to do a short warm-up again. For example, "Let’s just review what we were saying before the break" or "How are we doing so far?"
Always listen to the response to make sure things are warmed-up. If not, keep working on it.