Singing professionally is a tough business. Vocalists constantly condition and exercise their throats to stay in good form. When you make a living using your voice, it's can be a constant discipline to keep it in shape. Regular breathing exercises and proper fluids tend to be excellent choices for the marathon singers that perform almost every night.
Before a long day of tracking vocals in the studio, it's a good idea to have done some prep work. Don't drink any cold fluids before you start your recording session. It's also a good idea to drink warm tea or something that will soothe your throat. Take a decongestant if your sinuses are acting up and don't do anything that would cause you to sneeze constantly. Things like dusting the house before a recording session can be disastrous to your vocals.
If you're singing in a band or getting regular work to sing professionally, take time each day to warm up your voice. Keep exercising your lungs, throat, and jaw muscles. Just as runners need to stay in shape for the marathon, vocalists need to stay in shape for the performance.