I eye Dexter's fine motor skills throughout the day. A lot also has to do with hand eye coordination which goes right along with fine motor... but this is what I watch for:
1. Stacking Blocks (Our boys should be able to stack 2 to 6 blocks at this age. Dex does 3 accurately but seldom does 4)
2. Eating with fork and spoon
3. Brushing his teeth with little help (can he scrub back and forth? Dex sticks the tooth brush on his tongue and then drops it haha)
4. Removing articles of Clothing
5. Grasping scissors (yes he does have a pair of child safety ones), crayons, paint brushes.
6. Finger painting. Dipping finger in the cup and then onto his paper. You can also watch him pouring water into a container or place a car on its track. Does he miss his target, or does he hit it every time?
7. Scribbling
Things like that. It is easier for me to pick it out sometimes because I'm cross dominate. I do all gross motor right handed and all fine motor left handed... so I realize which actions are considered fine/gross easier.
Brushing hair, teeth, applying chap stick, writing, eating, zipping, stacking... all of these are fine motor.
If I lost my left hand I would look like a zombie with chapped lips and its pants undone <-- lol