Default - These are preselected values. See the Race Relationships chart in Images to view what the default race settings are. There are also some locational differences. As the cosmopolitan capital, residents of Solitude express less racism than elsewhere in Skyrim. However, Nords who are residents of Windhelm or part of the Stormcloak faction express stronger racism. I've also built several exceptions into the default settings to reflect individual character traits present within the game. Also, your personal relationship with a merchant is more important than any general feelings they may have toward your race and will override any general racial bias.
Bartering for goods and services is a centuries-old art. Recently, the idea of trading with your neighbors and within your community has received a big boost and taken on a modern spin. Combining our often-materialistic, ownership-based society with the Internet’s ability to bring buyers, sellers, and traders together, online bartering has sparked a wealth of new sites and communities.
Make the deal. After you've found a barter partner, get the agreement in writing. Make sure you detail what services or goods will be involved, the date of the exchange (or work to be done) and any recourse if either party reneges on their part of the deal. If you are working through a membership-based bartering association, they will likely provide all the structure and paperwork you need for the deal.
Some businesses that may not directly barter with customers may swap goods or services through membership-based trading exchanges such as ITEX or International Monetary Systems (IMS). By joining a trading network (which often charges fees), members can trade with other members for barter "dollars." Each transaction is subject to a minimal fee; the exchange facilitates the swap and manages the tax components of bartering such as issuing 1099-B forms to participating members. You may find a nearby exchange through the International Reciprocal Trade Association (IRTA) Membership Directory. Before you sign up and pay for a membership, however, make sure that members offer the types of goods and services you need. Otherwise, you may find yourself with barter money or credit that you cannot use.