Don't panic. You'll be almost useless the first 10minutes. Farm, try to last hit minions and use your abilities once a while (for the passive of the tear). Play with yout jungle: help him to contest the scuttle, if he's getting invaded go help. Once you reach level 3 try to do some dmg to the enemy midlaner with the combo (q+w+q+e+q) or even a (e+w+q) should be enough, then wait for ur mana to regen and repeat. Once you reach 6 try to gank top or bot if you are not out of mana (oom) and your wave is pushing the enemy turret.

Basically when in your team there aren't champions that need the blue buff, especially the jungler. They won't let you take the blue probably and you will run out of mana really quick (even faster than in the older patches).