It has a very long view range. In a large room, it is not unlikely it can spawn outside your depth of field view and the first you know about it is being shelled from long range.
It fires very slowly. Find a clear spot and wait for it to fire at you, then haul ass outta there. Snipe and fire while it is reloading. You'll see the muzzle preflare when it is about to fire. Relocate quickly and start again.
It also moves very slowly, so kiting it is easy. If you have enough mobilty, you can also jump right on top of it (see video below). It cannot fire at you from this position, so will just spin around aimlessly. Watch out, becuase you're a sitting duck for fire from others when you try this.
- Prior to version 1.0, the elevation of the tank's cannon was quite limited, meaning you could simply stroll directly underneath or fly over it and kill it easily. It can now aim through 180° vertical azimuth, so you can't do this cheesy move any more.
- "Tanks are the big giant well, tanks" -BlankSlateJoe