What to prepare yourself for when testing in Aikido is near impossible to give advice on. Even within the same organization the differences (preferences really) are always the difference between pass and fail. Even though we can all argue irimi-nage is irimi-nage -- it's not the same between teachers let alone organizations.
I remember my first test, I had practiced all the techniques for 5th kyu for 2 months straight, only to be scolded by our shihan that my attacks were all wrong during the test and couldn't really understand what he was even saying due to his poor English…and he almost failed everyone just because of that one reason but reconsidered when he found out we had never even seen his style of attacks -- and he was our shihan!
The hardest part is that each "style" has specific idiosyncrasies as how to attack, and how to hold the wrist, and how to roll, and what the names are called. It's near impossible to even discuss techniques (as you will notice on this forum) because of the diversity.
And while yes, people could give you very general advice like relax, find out what in particular your requirements are and concentrate on those things…that advice is the same thing you'll get on your SATs or an exam or any test for that matter, so I don't know how valuable it is.
Really you need to ask someone in your organization -- for instance I have never even seen a style that has 10 kyu ranks (other than for children to adult (i.e. the first 5 are children kyu ranks, and the next 5 are the normal adult kyu ranks)).
Hopefully someone from your style or organization will reply