Proper Microphone Technique
When the sound guy tells you to sing at the volume you’ll be performing at, do everyone a favor and actually do that. When you hold back during soundcheck either on purpose, in an effort to get more of yourself in your monitor later, or inadvertently, the engineer will probably have to turn up your gain, which will come back to bite you when you’re singing for real, in the form of clipping. That’s our word for distortion - the kind you don't want.
Proximity effect can be cool, if you’re a radio DJ or you don’t have a band backing you, but the all-lows/no-highs effect of choking up on (or choking on) the mic will pretty much guarantee that no one will be able to hear a word you’re saying, including yourself, and there’s nothing the sound guy can do about it, since they can only work with the frequencies that are available. If you only make available everything below 1kHz (where all that boxy sounding mud lives), that’s all you’ll get.
Want to know how to turn a cardioid (directional) mic into an omnidirectional mic? Block the phase ports at the back of the capsule with your fist. The mic needs to “breathe” (not really, but that’s a good way to think about it) i.e., have both the front and rear free of anything that will block the sound. You wouldn't cover up the front of a mic and try to sing into the back, right? If you block the back side of the mic, the sounds you don’t want to go into it won’t get canceled out (rejected) by the rear of the diaphragm, and will instead make their way into the front of the diaphragm. In a live situation, the last thing you want is an omni mic - that’s a great way to get show-stopping feedback! On top of that, the sound you’ll get will have an extra dose of proximity effect, ensuring you’ll have either terrible feedback, or a bunch of mud.
When a sound guy sees a vocalist mismanaging mic distance or holding the mic down by their stomach, they get pretty frustrated, and you probably do too! If you think you sound "thin" or "tinny," try getting closer to the mic before blaming the engineer. If the mic is too far away from the source, there’s nothing the sound guy can do to make that sound better other than try to get your attention and signal you change what you’re doing. At that point, it’s all on you. Mic technique is not hard - you point the part that’s supposed to catch the sound at your mouth. Pretend the mic is a flashlight and you’re trying to light up your smile. Pointing the mic anywhere else is just going to pick up a bunch of noise from instruments (we call that “bleeding”) or whatever else is around and making noise, like the PA system, and then you get feedback.
Notice where the mains are, and draw a mental line across the stage. That line is the do-not-cross line, beyond which the demons of feedback wait to ruin your performance and the audience’s ears. (Yours too.) Think about it - feedback is the result of picking up what is coming out of a speaker and then feeding the same thing back into it. The sound multiplies on itself and goes nuts. As soon as you step out past the line of no return, feedback becomes possible. Your front-of-house guy or monitor engineer rings out your floor wedges to make sure they don’t feed back, but that is not done to the mains, since it’s cutting frequencies that are needed to make you sound your best out front. For a PA that is properly flown above the stage, this is less of an issue, but it’s still not a good idea to test those waters.