I love spinning! Both fine yarns and the more quick, fun thick & thin yarns. I have found a little formula that I have found that works quite well for thick and thin. Divide your roving (approx. 4oz), with out tearing, in half, and then fold one half in half again, so you end up with a quarter of the roving. Tear the quarter section of the roving off.
Then spin the quarter section thinly, I use the fastest setting on my wheel. and then on a slower setting, I spin thick and thin with the 3/4 of roving. If you have not tried spinning thick and thin, you pinch the roving in a tick big and draft it until it goes quite thin, and then repeat this motion.
Once both of my singles are spun up, I ply them together on an even slower setting and voila, a gorgeous soft two ply thick and thin yarn. Perfect for a hat, or if you have up to 8 oz of fibre a scarf!