Good and Interesting question. 

Here are some to make the tester's job easier:

 1. Developers should perform basic testing before giving the product to the tester.
 2. Include QA from the beginning of the project, not when the product is ready to test.
 3. Work as a Team, not as two different departments [Developer & QA]
 4. As the developer, never ask the QA to ignore bugs. Also, it is not the QA's job to verify that bugs have been fixed.
 5. Support the QA if they do not have a clear understanding of the product. 
 6. Work toward the common goal of making a solid product. Do not think that you are the developer and they are the tester.