It's simply about looking further down up the casual chain, not stopping at the initial cause-effect: thinking about the effects of effect themselves (and, in third order, the effects of the effects of the effects, and so on).

A simple example of failing to do so and only considering the first level cause-effect:

"The British government, concerned about the number of venomous cobras in Delhi, offered a bounty for every dead cobra. Initially, this was a successful strategy; large numbers of snakes were killed for the reward. Eventually, however, enterprising people began to breed cobras for the income. When the government became aware of this, the reward program was scrapped. When cobra breeders set their now-worthless snakes free, the wild cobra population further increased".

Here's another one:

Caribbean plantation owners were tired of their relentless war against field rats – the rodents were eating into their precious sugar cane crops. Come 1872, a chap called W.B. Espaut had an original idea: why not bring over a few Indian mongooses – those unpretentious mammals known as enthusiastic rat hunters? Espaut travelled to India, had some mongooses captured and brought them to Jamaica. The problem – it soon turned out – was that the mongooses did not just kill rats; they killed birds, ate eggs, insects, useful reptiles, even small deer fawns. True, the mongooses also hunted and killed lots of rats; but they did not kill them all. In fact, the rodents continued to multiply – and so did the mongooses. Worse, both rats and mongooses carry a disease called leptospirosis, which can be lethal to humans. To cut a long story short, rather than getting rid of one pest, the hapless Hawaiians ended up with two.