Whenever that music, which goes, dun dun dun, dun dun du-dun, dun dun, things go B-A-D. I also know the enemy sends everything they got at me when the music plays.
Hope that the enemy destroys the Atom Sub and the remaining Subs ASAP, because if they don't and the subs beat up the base good, it's just all gonna turn out like ppppppppphhhhhhhhhhbt.
I think I know a way to take down battleships, carriers, or tough ships harassing you. First, if they're attacking your base, deploy a Frigate and a couple of PT boats to distract him while the missiles and artillery guns and the Torpedo Battery, and then deploy about 10 or 12 Submarines, 6-8 torpedo bombers, and an Atom sub. I DO NOT recommend Bombers, because things will just end badly. I learned that the hard way several times. ._.
The best strategy is to upgrade the towers you currently have before buying some new ones. That way, there's a chance you will defeat the bloons. I'm saying there's a chance. I'm not guaranteeing you that it will work.
If you notice that you splat a Biter or Fuzzle and then another one comes in and kills you, then the Bait on the Hook tactic is successful. Try to be alert for this. It can sneak up on you.
Looking to get the Impressionist and Awesome Combo badges at the same time? All you need is 2 Green Glooples, 1 Stickie, 1 Meltie, and 1 Biter, or 2 Green Glooples, 1 Biter, 1 Stickie, and 1 Sharp.
Don't fall for Torchies. Wait when they extinguish and splat them, unless you have armor. If you see it might set on fire, don't splat it. It's better to not deal with Torchies at all sometimes.