To be clear, I understand you can not tell me how I need to prepare. So please share with me/us how you relax and put your mind in place for Aikido, and maybe a statment about why it works for you. Perhaps from reading how you get ready, myself and other readers can consider how to blend your experiences into ourselves.
This may not be the answer you require .My teacher states that it is essential that you as a student acquire the following;
1.To leave 'baggage ' at the door of the dojo.That is to say dont bring you everyday problems onto the mat.We are training in Aikido not attending therapy sessions.
2.Cultivate a mind that is like an undyed piece of silk.By this my teacher means view the techniques as though you have just seen them for the first time.
One of my own personal habits is to simply take a deep breath , hold it for a few seconds maybe 10 /15, then shrug my shoulders , raising them upwards, then releasing the breath and dropping the shoulders.This is really all I need to get ready for practice.I am not too fond of lots of stretching etc.Maybe because I am stiff and a mature gent.
Hope this helps.