While you are freestyling, have another MC control the mic volume, moving slowly or quickly, to different levels. You will have to pay attention and change the loudness of your voice and the proximity of the mic to your mouth to compensate and keep your sound at the same level though the speakers.
Some people are too loud on the mic, and some people are too quiet. Sometimes it’s because of poor mic-holding technique, but generally it’s a problem of not listening. This practice is all about listening to what you sound like and adjusting your volume accordingly. It can also help you to develop louder or quieter styles, and to expand your dynamic range. When you get up on the mic you can’t always expect a perfect sound level. Sometimes it’s a quiet (or broken) mic, or a bad sound setup, or sometimes you’re following a quiet MC and the mic is super hot. Without this skill, you’ll either not be heard, or your voice will sound too loud and annoying. Train to listen and respond with a good voice level every time.