I personally play with the energy meters on the screen. The first online match I won I did by submission. I had played nothing but the PC up until that point and was winning by knockout left and right but never got a submission win. I realized after about 2 minutes in the first round that my opponent wasn't very good with the ground game (he wasn't able to sweep me or advance position) so I decided to take him down, put a few elbows into his face to wear his energy down, and when he had run himself down I slapped on the submission for the win.
I usually base my actions off of how much energy my opponent and I have. That way I can decide if I want to drain him with strong shots, wear him down with smaller shots, or pounce in for the kill.