The biggest risks
In a buffet, not only do you put yourself in a line of hungry people, you also put yourself in the line of danger. Some food needs to be at the right temperature, otherwise, it may become deadly. Sushi and oysters are some of those foods. In buffets, they serve it in a single line. Skip those raw fish, meat, and oysters for now. Except, of course, if it really has its own storage in the buffet that makes it safe.
Another thing you should worry about is the risk of cross-contamination. Watch out for the people who use a single spoon in eating and getting food. Avoid using chopsticks to eat and pick sushi. Some people change their mind after they have picked it up. If you see this kind of behavior, do the good thing and inform them. If they look like someone that considers constructive criticism won’t help, alert an employee.