1)Mashing the potatoes is the main step, you can puree them in a blender or grate them using a fine grater.
2)Dont add too much maida, if your mix is sticky, then add another tbsp of maida. If you add too much maida then the jamuns will get hard.
3)Fry the jamuns in low to medium heat, a trick is, once you add jamuns to oil, dont stir immediately, leave them for a min them stir so you dont break the balls.
4)These jamuns will absorb the syrup faster, so if you leave the jamuns in the syrup for long time, then they will break up.