The best tip for the ones who are starting to play as Cho'Gall is: YOU ARE 2 HEROES, BUT U CAN STILL DIE, and DONT FIGHT MORE THEN 2 PERSONS ONLY BECAUSE UR A JUST RELEASED OP GUY.
I say that ^ for personal experience, don't think that because you are a big fat guy with big damage and big health you will be undying.
Also a great thing is to have a voice chat to speak with cho, the combo build requires comunication.

*Voice chat is totally needed
*must have a synced build with cho
*training is the best way to do this right
*use your ult to its full use, channel it as much as you can on lvl 20