I would suggest the following:

Find a large empty area to practice, such as an empty parking lot.
Accelerate until you feel stable, and try hard to ride a straight line. If you're in a parking lot, try riding down the "spine" of one of the rows of parking spaces. Really focus on the line, and making sure your front tire follows it.

Once you can reliably ride in a straight line at a moderate speed, then slow down. Keep riding in a straight line at a slower and slower speed. Practice until you can ride very slowly without falling off. Eventually you'll be able to start up or slow down without wobbling hardly at all.