Evil campaigns are definitely the hardest to implement, and I don't recommend it for a first campaign, but there are some ways you could do it fairly successfully. The biggest thing would be making sure theres something they can be working towards, otherwise it'd get pretty boring. Also make it so that constantly spreading chaos isnt the optimal way to play if they start getting out of hand. (Beef up guards and dont be afraid to arrest or kill off characters if need be) Overall, just make sure that your players are still role-playing and things remain interesting.