How would you advise someone to learn how to negotiate and get better at negotiation?
In addition to my own deals which I obviously work on, I also, some time ago, took on negotiating deals for others since it was fun to do. I ended up having enough takers that I started to have to charge for doing that. While the amount I am paid wouldn't make it attractive full time [1] (besides there are no residuals which I like) it still is something I do just to keep my mind active and since I have the flexibility to take chances where the outcome isn't as important. And to me, it's fun. I get a great buzz from having the correct analysis lead to a positive outcome. In some ways it's better than money.
Another thing that is good practice is simply to try and make deals for others that is to put deals together or what I might will call "shoot the gap". I do that all the time. I'll see something that I think could be helpful to 2 different people and without even getting paid for it I will try to convince both of them that they should get together on some business issue. Then when if reply or are negative I will try and overcome the objections to make a deal happen.
Risk always enters into negotiation. If you are willing to lose you can take more chances because you aren't as worried about going bust. If you can't lose (you really need something) you have to be more careful and can't be as reckless.
[1] Because in the end it's more money in my pocket doing things on my own account time wise although there is a great benefit to doing it for others as well I gather more data because there are more situations to work in and around.
Playing Diplomacy (and similar games) works for some.
P.S. I'd like to get in touch for some thoughts on negotiation.
Read 'Getting to Yes' and 'Bargaining for Advantage.' Use the principles when making any large purchase or changing jobs.
Most retail cashiers can also give 10% discounts without approval. Find opportunities to negotiate.
Buy things on craigslist and be patient.
If you read the books, you'll also see more everyday situations and compromises as chances to use negotiating skills. There's no reason it needs to be money.
If you're in software you can also read patio11's valuable thoughts: http://www.kalzumeus.com/2012/01/23/salary-negotiation/
http://www.amazon.com/No-Only-Negotiating-System-Need/dp/030...
And there's a reason that's the title :-).