1. Invest in a stress ball. These are usually made of gel or foam and fit in the hand. Some health depts and banks give them away. I've even seen them as promos for buisnesses and at fairs. An idea of an exercise would be to squeeze it 20 times.
2. Do Silly Putty or clay. I once had an OT that used something that looked like Silly Putty. She would have me press down with a finger to make an indent. Then she would take and re-shape, and then have me press with another finger.
3. Get a handwriting book. It's just easiest (and cheapest) to use what the kids use.
5. Snap your fingers
6. Touch thumb to each finger (a lot of neuros will have this in their exam)
Some activities are good. Try for 5 min with the bad hand before giving up and going about your usual way. Things like washing your hands, wiping a table, and tying your shoes. In everything you do, just try with your bad hand (this may only mean to reach toward it). (I started turning off a light with my bad hand. This meant reaching to the switch. I then let gravity do its job. As my hand fell, it would brush the switch and turn it off. Now I don't have to do that anymore.)