1.If your fighting a poke mage (Lux, Xerath, Ahri, etc) most people would think to to give them a wide berth in the early game, which is exactly what you DON'T want to do. If you grabbed Doran's shield in shop first item (which you always should get), it will heal back a portion of their poke damage as you farm minions, and of course you should always try to stay back when no killable minions are in range, use Q to pick off backline minions from a safe distance, auto frontline minions, and farm as many as you can. If you can proc Grasp in the meantime that will help leaps and bounds in healing you and damaging the enemy champ.

2. The reason you want to do the above is because you want enough gold for the items that matter. Always get either cloth armor or Null mantle first in lane (depending on the enemy's main damage type) then a ruby crystal to back up that extra Armor or MR.

3. Since your Mid lane, you can do a lot to help out teammates, whether it be using your ult to roam bot and keep them from feeding or rushing to the Ally JG to help them win a fight. Ornn Mid has an early game advantage with his tankyness and does a better job than most of supporting his team with his abilities early on. Always keep this in mind, not just as an Ornn Mid main, but as a Mid player in general.

4. The reason you want to do the above is because you want enough gold for the items that matter. Always get either cloth armor or Null mantle first in lane (depending on the enemy's main damage type) then a ruby crystal to back up that extra Armor or MR.

Abuse Grasp Early: Combined with Q's slow at Lvl 1, it is very easy to proc Grasp early on and make trades against burst champs (fizz, LB, Talon, etc) go in your favor

Tenacity Shortens CC: True Ornn mains know about the Pseudo-Unstoppable W, that was nerfed a while ago, and cc against a champ that requires mobility hurts. However, when Tenacity is combined with the W that negates all cc for it's duration, it can make short bursts of cc nonexistent and when combined with Merc Treads severely decrease the effect's of CC, especially when you have to deal with those besky ranges cc mages (DAMN YOU BRAND AND LUX).

Coup De Gras: Helps immensely in taking out champs that are trying to get away in lane or that pesky ADC in the backline that you need to make go away after you used your Ult and E to run straight into the backline. In the words of Todd Howard: "It just works".