[rgraham]

Practice when you have a chance.

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/