Drawing individual hairs is the most fine-motor-demanding task in makeup, so the adaptations matter more here than anywhere.
Brace everything. Elbow on a table, the heel of your hand against your cheekbone or temple, and the pencil held close to the tip. A braced hand makes short controlled marks; a free hand makes long ones.
Make the marks shorter than you intended. If your hand shakes, halve the length. Many short marks read as hair; one long wobbling mark does not.
Use magnification and front light, then step back and check at 1x. A standing lit mirror with a 10x panel makes the gaps visible, and the 1x check is what stops the brow being over-drawn.
Try the gel-first order. Brushing a tinted fiber gel through the brow before you draw anything gives you a base of body, so the number of marks you need to draw drops substantially. For some people that is the difference between an achievable brow and an unachievable one.
Or use a gel alone. A one-pass brow gel such as GUIDE Beauty's Brow Line gives a defined brow with no precision drawing at all. That is a legitimate answer, not a lesser one — see best brow gel for older women.
And wipe off and restart freely. A cotton bud with a little micellar water removes a brow in seconds, so nothing here has to be right first time.