Train in an orthodox style. Then add your own bits to it to make is unorthodox. For unorthodox, the best probably Muay Thai, because it teaches how to hit thing really freaking hard. Then change it up, chance your stance, footwork, hand positioning to make it unorthodox. Plus, if you train an unorthodox styles you will have very little training partners the mimic the orthodox style of most fighters.
For example, I am extremely unorthodox on the fround and on the feet. I train Muay Thai, I also have a black belt in Shaolin Kenpo. But I switch stances often and have learned to use strikes to transition and set up other strikes. Sometimes I will throw a looping rear handed hook and step my leg forward into a southpaw stance while punching and either fire a left head kick or straight.
Joseph Benavidez - Jose Aldo - Joe Lauzon - Demetrious Johnson - Mark Munoz
-R.I.P. World Extreme Cagefighting-