Enemy shots can be destroyed. If you see one coming at you, fire your cannon and the shot will be neutralized. You can also destroy an enemy tank while the shot is in mid-air and the shot will automatically neutralize.
Dodge Enemy Shots
If your cannon is damaged or you don't have time to shoot the enemy shot, you can dodge the shot. Simply move so that the shot is off of your view screen and it should go right past you.
Even at night or during a fog, don't give up hope. Your radar, as long as it's undamaged, can still locate enemy tanks where normal people couldn't, and when an enemy fires, they illuminate for a second, giving you a lead on where they are.