That's it, basically. If you have something important to influence about, learn everything you can about it. Read everything you can find, talk to everyone who knows more about it than you do. Don't limit yourself by looking only for support or justification of your point of view. Get familiar with all the counter-arguments and all the potential threats that are related to your idea - all the needs and fears that might arise for someone who actually had to agree to take action on it. Think yourself into the mind of someone who would be unalterably opposed to doing what you want done and then see what it would take to change your mind, even to warm up to the idea just a little.
Develop a list of benefits and costs for taking action - not just for you (although that will be useful), but for the person or group you hope to influence. Do a risk analysis. Identify what could go wrong and how such problems could be prevented or mitigated.
Be sure to do this from your target person's point of view. Think about the risks of not taking action at all.
Anything you can do to stimulate dissatisfaction with the status quo may help move your idea forward. Some ways to do that include:
Influencing people generally means getting them to change or modify the way they think, feel, or act. Behavioral scientists, such as the late Richard Beckhard, Ph.D., of the Sloan School of Management at MIT, have suggested that change occurs under the following conditions:
Each of these must exist in sufficient strength to balance the perceived risks of change. The information you gather about the issue can serve to strengthen the other person's understanding in any of these areas.
When you have gathered the information, consider how best to present it to the person you want to influence. This kind of information is often most effective when the other person has a chance to absorb it on his or her own before you discuss it. You will also want to think about choosing information that focuses on the merits of your idea, rather than criticizing the status quo or viewpoint of the person you want to influence. It's best if you let the other person do that. It is easier to get someone to think about your idea as another, more useful alternative than to escape unscathed from someone who is fiercely defending his or her previous choices and decisions.
Even with all the homework you are doing, it is possible that you will persuade someone to agree that the situation needs to change, without deciding that your preferred solution or idea is the way to go. Consider possible alternatives and how close they would come to meeting your need or achieving your goal. You may have to shift to an alternative if it looks as if you will not achieve your original goal. Having already considered alternatives gives you some useful flexibility.
The best thing about doing your homework is that it gives you confidence . . . Confidence that you know what you are talking about . . . Confidence that you are prepared to deal with questions and objections. Confidence has a very attractive quality: it lets the other person know that he or she can trust you on the issue. That is, unless you use your confidence in a manipulative way, by asking "trap questions" or otherwise putting down the other's position. Having confidence enables you to build up your position without tearing down that of the other. That way, you will not have to deal with defensive and self-protective resistance to your ideas.