Most people say to practice with the off hand and I agree. But I would like to suggest taking it a step further. Exercising both sides of your brain can help you to be more ambidextrous, IMHO. When I teach my qigong and taiji, I emphasize this and work it with my students. Some simple things to try at home. Start small. Every notice how we have a "favored" way of doing things? Even something as simple as folding our hands or crossing our arms. We pretty much always do it the same way. I challenge you to be aware of it and change it up from time to time. It will feel funny at first, but after a while, it will feel natural and you will have to think to determine which way you are doing it. With the advent of issues like Alzheimer and dementia and such, I have heard of some doctors suggesting exercises to work both sides of the brain too. Other stuff to try, brush your teeth with a different hand at night and in the morning, eat with your off hand, etc. When I was in intermediate school, I believe, my first Sifu taught me a butterfly knife form. In it, there was a part where one hand made one pattern and the other made a different pattern at the same time. My first thought was, "This is so cool! It's hard to do two different things at the same time." But I remember that and think it can be useful. In Escrima, we trained using both hands as well as one handed with either hand. So all this rambling came about because I got up earlier than my family and let my mind wander over a quiet breakfast. It was leftover ribeye and prime rib, by the way. With a banana and coffee. Leftovers can make great fast and easy breakfasts. I will often eat with my off hand. In this case, switching the knife and fork hand around. It's also fun to use chopsticks with the off hand. Impresses the heck out of folks if you switch successfully. Try it and see if it helps your off side dexterity and at the very least, it will make you more aware of your body and what you may be capable of. All part of preparation, right?