Quick question.

I am currently serving in the USN and will be a tattoo artist when I get out. I will seek a formal apprenticeship, and i will do it the right way. The question, would it be a good idea to buy a kit online and practice with a calligraphy pen and a disposable tube while the machine is running so i can build strength and endurance?

Don't worry about equipment at all just work on your art. Script and calligraphy are great skills to hone. Lets see a link to your artwork.