One piece of arithmetic prevents most phase misery: keep the second mic three times farther away than the first.
Build the Mix From the Drums Up, Not the Vocal Down
Most mixes start in the wrong place, and you can hear it in every single one of them.
Parallel Compression for Vocals: When It Works, When It’s a Crutch
It’s not a magic vocal button. It’s a specific fix for a specific problem, and using it without that problem just makes things worse.