How would you go about testing a new functionality?

For testing a new functionality as a QA the below steps should be followed:

1. Read the requirement document and understand all the user requirements related to that functionality
2. Create test conditions and test cases according to the assessed requirements
3. Prepare a Requirement Tracebality Matrix (RTM) to check prepared test cases have covered all the requirements
4. Get all the test conditions and cases peer reviewed
5. Get a Business Analyst (BA) walkthrough
6. Execute the test cases and report the bugs (if found any)
7. Re-test the fixed bug

And when all the bugs are fixed and re-tested the software is ready to be tested in UAT environment and after that ready for deployment in production environment.