Doing some simple exercises can help you become ambidextrous. One such activity is practicing your handwriting using your non-dominant hand. For example, practice writing with your left hand if you are a rightie. Left handed persons can practice using their right hand. Your struggle to even draw a straight line can be frustrating at the start, but it will improve over time.
Don’t stop with writing. Find other things that you can do with your weaker hand such as brushing your teeth, picking up things, or lifting heavy objects from the floor. If you are into sports, practice the drills using your non-dominant hand. For example, in basketball you can practice shooting and dribbling with your left hand if you are right handed.