I like to use a clip on wireless microphone when I sing, but I have difficulty finding a suitable place to wear it. I know I drive the sound people crazy whenever I show up for a performance, because I will clip the microphone to my shirt, my jacket, my tie and my collar during a rehearsal and still not be happy.
I've heard my own heartbeat get amplified through a wireless UHF microphone before, and I also have to make sure the clip on mic doesn't pick up my breathing. I tend to take large breaths while I'm singing, and if the microphone is too close to my mouth, it will sound like a loud roar. My favorite kind of microphone to use is a handheld wireless microphone, since I can move around the room and control the volume by moving the microphone closer or further from my mouth. I can't do that with a standard lavalier microphone.