A Spinner's Control Card is a clear lucite card with the different thickness of yarn on it. You lay your spun single (or plied yarn) on in to determine the number of wraps per inch, which gives you an indication of how thick or thin, and how much variation is happening with your spinning. Here are some links at random, NAYY:
Also, I forgot to mention oil for your spinning wheel - lots of people use a lightweight oil such as sewing machine oil or 3 in 1.
And, if you are going to process your own wool, you would want either some hand cards or combs. (But, I think I am jumping ahead here!)