What are among the worst ways of dealing with depression?

Not dealing with it. Worst way is denying and refusing treatments. Depression is very common but can be very debilitating without help. Self-medication with drugs and alcohol is another.
Doing Nothing. The worst thing you could do would be to do nothing. This would include isolating yourself and rejecting help from others. Also, it would be a bad idea to try to self-medicate through excessive alcohol use or illegal drug use. In addition, it is not healthy to engage in other risky behaviors as a way of trying to make yourself feel better.