Good and Interesting question. 

I have some tips to share which make tester work easy if developer co-operate. Tips are :

 1. Developer should perform basic testing from their side before give product for testing to tester.
 2. Include QA from beginning of project not at the time when product is ready to test.
 3. Work as Team rather than two different department [Developer & QA]
 4. As developer never request to QA to ignore any bugs. To find bugs and verify that if those fixed or not is duty of QA.
 5. Support to QA if they do not have clear understanding of product. 
 
 6. Work for common goal to make product solid. Do not think that you are developer and they are tester.