If you know that youre weapon is going to hit an enemy, use ice block. Becuase there's a chance that you will die before your bullet fire will hit the enemy. (Only use it when you think and know that its going to hit them)
If going for a surprise attack or finishing off an enemy, the best tip is to blink in the air. And when youre close to your enemy FIRE. Doing this makes it easier to hit people