My best tip for round cookies: When the cookies come out of the oven, immediately use something round (a mug, large round cookie cutter, biscuit cutter, etc.), place it over a cookie, and swirl it in a small circle. The cookie will move around on the cookie sheet a bit, and that's okay. The cookies are still warm and soft, and you'll be able to easily mold them to the rounded shape of the cutter/mug. Repeat with the remaining cookies, and your whole batch will be round!