Vocal

Volume. Don’t hold it back. Too often the vocalist sings too soft during the recording session, whether because she/he thinks it would sound better, or because of the environment. Unfortunately the opposite is the truth, it will sound worse. Don’t be shy, sing loud and proud

Warm up. This is really important. This can make really big difference
If you can sing better if you’re alone, then tell the rest of the band to leave. There’s no need to ruin your take

Hot tea. With lots of lemon, possibly without sugar, with just a touch of honey if you like so. It can make very good things with your throat