Things are getting harder by now, the most annoying most likely being the snakes. If you find yourself becoming surrounded by these then try and escape as quickly as you can. If you get swarmed their tails may cover their heads which will make it very difficult for you to kill them. Once you are a safe distance away aim for their heads. If things look pretty bad, go ahead and use your bomb. Remember, you don't get points for enemies destroyed from bombs but it will keep you alive, and your multiplier up.