Watch Your Health
Speaking of health, your character in Umbrella Corps is actually really squishy. You can take about three or four consecutive hits from an enemy before you get downed, and have to restart the level completely. The more damage you take, the darker and redder the edges of your screen will become. Be sure to keep track of how much damage you’ve sustained, and run away from your enemies when you feel like your health is getting critically low. A good rule of thumb is to back off from the zombies after just a couple of hits.
Thankfully, your health will regenerate over time, even without the use of a herb. Once you’ve gotten away from your enemies, either look for a herb, or simply wait long enough for the red edges to disappear from your screen. Getting your health to refill back to full actually takes a little longer than you’d expect, so try not to engage any enemies while you’re trying to recover.