You could use a tablespoon or ice cream scoop to get perfectly-sized, uniform cookie dough balls (or meatballs), scooping, leveling, dislodging into your hand, and then rolling so they're round balls instead of half spheres.
Or, you could do it an easier way.
We learned this trick from the February/March issue of the now-defunct Publix FamilyStyle Magazine:
On a piece of parchment paper, roll out or press your mixture into a rectangle.
Trim the sides so they're straight. Roll the side bits into a ball or two (or if it's cookie dough, eat it and tell no one).
Using a sharp paring knife, cut the rectangle into even squares. To make sure you're getting even squares, you could use a ruler, but I use my fingers (they already have food on them): Place a certain number of fingers on the dough, mark with a little knife cut, then cut all the way along.
If your recipe calls for each ball to be a certain size, you can play with the square size to see which will give you what you're looking for. Cut one row of various sized squares, roll to see which is the right one for the job, pick the winner, then cut the rest of the dough.
A New Way to Dinner, co-authored by Food52's founders Amanda Hesser and Merrill Stubbs, is an indispensable playbook for stress-free meal-planning (hint: cook foundational dishes on the weekend and mix and match ‘em through the week).