When practising circles, here's what I would do before a drawing session...just draw lots of circles on my sketchbook, with a single stroke, of different sizes and whatnot.
1.draw a box first,
2.divide it into four,
3.draw diagonal lines to form an X across its center.
4. In each small square (4 total, since you have divided it into 4), split the diagonal line in it into roughly 3 equal lengths.
5. Draw ur circle.