Early Game Strategies
Early on, the game proceeds at a very easy pace. You have a small, manageable herd so make the most of it while you can. Fill the milk bucket to the brim and you'll get an extra $100 bonus for dumping a full bucket of milk.
If the evil cow tipper appears, be sure to take the time to fire twice at him to, umm... end his intrusive ways. Not only do you get to decorate your lawn, but you will also get a hefty $500 bonus.
You should take advantages of these bonuses now, as they are categorized as...
Risky Behavior
"Fate Smiles on the Stupid," and in Udder Insanity, we encourage risky behavior by giving bonus points for it!
Filling the bucket completely is a bad idea since it leaves you without the ability to remove milk from a cow that's near explosion. To reward this dangerous act, you will get an extra $100 every time you dump a full bucket. A full bucket contains $300 worth of milk, so you will get $400 total. That's a 33.33% increase in yield!
Killing the cow tipper is another risky maneuver as it requires you to fire the shotgun twice. There is a little delay incurred each time you shoot, and you could be using that extra time to scurry towards an over-inflated cow.
Mid Game Strategies
At this point, you will have around five to seven cows. The cows don't accumulate milk as quickly as later on in the game, but things are more complicated because your herd is larger. Filling the milk bucket is a little risky here since you have started accumulating new cows to worry about. However, you still have a chance to capitalize on nuking the cow tipper for bonus points, so do it while you still can.
Later Game Strategies
By now you have a full herd of eight cows and they will all be producing milk at prodigious rates.
At this point, filling the milk bucket to the brim is akin to suicide. So is killing the cow tipper: in the time it takes to fire off the two shots needed to kill him, you'll probably lose a few cows from lactose overload.
In fact, it may be better to simply let the cow tipper run away after the first shotgun shot. A countdown is used to set when the cow tipper appears. This countdown is started after the cow tipper runs off the screen or is killed. Killing the cow tipper will cause the countdown to his reappearance to start immediately. If you let him run away, he'll take the time to run away before the countdown is set. While killing him may be gratifying, letting him escape will give you that extra time before he reappears.
Another important skill is being able to "milk and move." By this point, you shouldn't be trying to squeeze a cow all the way back down to its normal size. If you do that, a whole bunch of other cows will undergo milk-related death. It is better just to milk enough to keep the cow from getting too close to death before coming back to her again.
Additional Tips
Here's a couple of hints to help keep your herd alive:
1) Learn the different stages of milk production:
Notice that the cow's ears raiser higher as she approaches over-lactation. Use the ears as a measure for when to milk a cow. Additionally, a cow explosion is directly repeated by a spasmic waving of the cow's tail. The tail spasm is the final warning before a cow explodes.