I was having a tough time getting a good connection on my battery cable, so I decided to tackle the issue. A simple trick to try first is to soak the end of the wire and the terminal in either Coca Cola or baking soda & water. Either will eat away at the corrosion causing the issue. Of course if Coke is doing that to metal what do you think it is doing to your stomach?
This time around I just wanted to have a new connection, so I cut off the last 3-4 inches of the wire and got to new, clean wire which had been protected by the rubber coating. I then put the new terminal on and hammered it closed around the wire with a portable devise. The last thing I did was wrap the end of the wire and a bit of the terminal to protect it. Since this was my positive cable I used red rubberized tape.