One of the things that I use is what I call “standing a Welker away from the microphone” (named after the great Frank Welker). Take your hand and make the “hang loose” sign from Hawaii. (thumb and pinky finger extended – middle three fingers folded) Put your thumb up to your lip, and the pinky finger to the microphone and (generally speaking), that's how far away from the mic you should be before you start. The engineer will tell you if they need you to come closer or farther away, but at least that's a really great baseline of where you need to place your face in front of the microphone to get the optimum sound when you're creating a character. From that, you don't want to deviate too much. You don't want to go to the left or to the right because you're going to do what we call “off-mic” or “off-axis”. You need to stay completely stable in front of the microphone so it doesn't change the performance.