I sometimes run sound/mix for events/musicals/plays/concerts. Some tips…
Roll-off the low end, there is nothing there but rumble, hum and noise. Use a high-pass filter.
This one tip alone will make a big difference in vocals. (will cut out background ambient noise, AC/fan noise, wind noise, rumbling noise, footsteps, etc)
Make sure there is enough gain but not clipping.
Use a condenser microphone instead of a dynamic microphone (note: will need 48V phantom power)
If the “ss” aren’t intelligible, a little boost around 6khz to bring some nice sibilance, but not too much. Just give it some “air”.
Depending on voice, a 1khz slight bump will improve intelligibility. But not too much as ears are most sensitive in this frequency too.
If you’re talking softly, or vary your volume levels too much, compression will help as it makes the overall levels more constant… it boosts the quiet portions, and compresses back down the loud portions of your audio.