Don't (unless you really don't like writing software).
The answer I've come up with is either become a project manager (not working out so far, nobody wants to hire a PM without PM experience here, no matter the certifications), or start your own company (which might be the right answer in your case).
To be honest, I think both documentation and test cases are overrated, I do believe in lots of user testing and feedback, which is the most important thing (and that's why I believe any methodology that encourages frequent user feedback is a good thing).
What I'm writing about applies for the usual business or customer facing apps, I don't know about other fields (maybe for scientifical or medical or whatever apps it's a whole different story).
The answer I've come up with is either become a project manager (not working out so far, nobody wants to hire a PM without PM experience here, no matter the certifications), or start your own company (which might be the right answer in your case).
To be honest, I think both documentation and test cases are overrated, I do believe in lots of user testing and feedback, which is the most important thing (and that's why I believe any methodology that encourages frequent user feedback is a good thing).
What I'm writing about applies for the usual business or customer facing apps, I don't know about other fields (maybe for scientifical or medical or whatever apps it's a whole different story).