1. Every test case should be accurate and tests what it is intended to test with clearly mentioned preconditions, steps to be followed and the expected result.
2. Language should be simple and any person should be able to understand.
3. There should be no ambiguities as these would be distributed across other testers who are unaware of the functionality of the product and can only understand by going through the test cases.
4. There should be no hidden information with any mention to environment details. Example: The website to be tested on all browsers. Here there should be a reference to the browsers to be considered.
5. It should be reusable. As the product has different versions, the test cases written for the first version should be in a reusable format for the earlier version also.
6. It should be traceable to requirements. This gives the coverage details as to what requirements were covered.
7. It should be compliant to regulations.
8. Each test case should be independent.
9. Every condition/flow should have a separate test case.
10. Always write small test cases.