Once Laning Phase begins, stay close enough to the enemy for your passive to mark them. Immediately after using your passive on them with a basic attack, E off of them and basic attack one more time. Do this as often as possible.
(The effectiveness should be clear to you afterwards. If they have massive armor runes, you may end up with an equal amount of health as them after. In that case, auto attack minions to regain health ASAP)
After you get Q, harass as much as possible with it (while waiting enough to not run out of mana). Don't stop trying to get the double passive attacks off as well. You are virtually guaranteed the first mid lane kill by doing this.

If you are having issues keeping more health then the enemy, grab vampiric scepter ASAP and after every attack on the enemy champion, auto attack minions to generate health. Once you have more health than them, repeat the steps.

After their jungler has enough time to get either jungle buff, ward one side of the river and stick to it. (By the time it's gone you should have your W) Any time they make an aggressive move, use w to reveal all around. In the event you are being ganked, DO NOT panic and use everything to get away. Wait for the one who can stop you to do it while staying on your side of the lane, immediately after it is finished, E off the closest enemy. Then flash if necessary.

By level 6 you should be doing well in your lane, so if you use your ult to kill their mid laner, avoid double casting it if possible until you make it to either top or bottom and E on that lane for a gank. If too low after mid kill {<25%}, use ult's attack speed to regen off minions

If your ult is ever up while another lane is about to get ganked, ping that you're incoming to team and ult down there immediately. Try to avoid double casting it if possible until you get back to your lane.

By now, the enemy should be trying to dive through your team to get to you. Remain passive on the outside of the fight until you are assured they don't have enough crowd control left to stop you.

DO NOT USE YOUR ULT UNTIL THERE IS ONLY 3 LEFT