Re: Being ready
At 6th kyu you are not expected to be perfect. My teachers say that they just want to see that you understand the shape of the technique and that all of the pieces are there. When I look back at my 6th kyu test I sure know I had two left feet and things were kind of stiff and awkward yet. But if sensei says you are testing then you are ready.
If your dojo has a syllabus for testing ask for access to that and ask one of your seniors to help you work on things outside of class. No test is perfect but you want to put some effort into preparation for it.