For example, when meeting someone for the first time, notice their stance. If so, try to do the same within a minute or two. Are their legs spread apart. Spread yours the same distance. You have just reached their comfort zone.
People like to be around people like themselves.
It's familiar and comforting. The same holds true if they are sitting. Try to position yourself just as they are. If they are leaning back in their chair, lean back exactly like them. If they have their arms dangling nonchalantly, you do the same.