Hi. This is my take on Heimerdinger. It's different but effective. I don't start with a Tear of the Goddess but always with Catalyst the Protector then upgrade to a Rod of Ages. This is because Heimerdinger dominates with his pushing power early game and mid game. It makes no sense in buying a late game item. Remember, the longer you survive, the more damage you deal.

http://farm8.staticflickr.com/7234/7310703000_dd70b473cf_b.jpg

Pros
Pusher
Harasser
Tank
DPS
Low skill champ

Cons
Slow
Requires thinking
Turrets at easily destroyed late game
Very easily counterpicked

Don't ever buy a Tear of the Goddess!!!, it is an item for late game only and Heimer is particularly weak at late games, the longer you drag on the weaker he becomes. Heimer is not a spam champ, the Catalyst the Protector and blue will provide all of his mana needs The cooldown on his skills simply doesn't make him viable for Tear of the Goddess, you're not going to spam his turrets or grenade or ultimate. So don't waste gold on it.

Instead get a Catalyst the Protector early and then a Rod of Ages, Rylai's Crystal Scepter. You should be able to push the mid tower down while being safe from ganks.

After getting the Guardian Angel and Zhonya's Hourglass. You are almost impossible to be killed.

Pretty basic runes, gives ability powers at early levels and defensive stats at later levels.

Both kiting spells. Don't panic and quickly use them when enemy jungler ganks. Place a turret between the jungler and run into the bush if necessary. If jungler follows, then place another turret in the bush ensuring they take maximum damage from chasing you. Only use the grenade when they are right up to you.

Nice.