Do not be too confident yourself, even you are so experienced. Doing mistakes are most probably inevitable. Do not neglect the other side's problem. You can not negotiate effectively unless you understand your own interests and your own no-deal options. At least, you need to understand the problem the other side's perspective. It is vital to try to understand in depth what the other side really wants out of the deal. Being a guy driving the deal from your side of the table to the guy who understood the deal from the other side. If you want to change someone's mind, you should first learn where that person's mind is. That is more effective to understand other side's mind rather than to enforce your mind. Sum up, do not only focus on your problem. Solve the other side's as the means to solving your own.