You asked specifically about the Soviets, but I'm going to start a little under two years before the Soviet invasion, because that's when communists within Afghanistan orchestrated a coup and took over the government. To make a long story short, they tried to implement all the standard communist reforms—division of land, collectivization of agriculture, canceling of debts, etc. etc.—and it went so abysmally that the Soviets intervened out of fear that the US would use the chaos to absorb Afghanistan into their sphere of influence.

So. In the sixties, Mohammad Daoud Khan, the then-current Prime Minister/dictator of Afghanistan started sending Afghans to Russia and Eastern Europe for military training. There were already Afghans going to Western universities for civil training, so this was a way to balance things out and make sure Afghanistan remained neutral. As a result of this military training, hundreds of Afghans were returning to Afghanistan having absorbed Marxist ideology along with military learnin’, and began to spread this new framework through which to understand the world—one that dispensed with all that “heaven and hell” nonsense. These ideas spread to Kabul University, the main university in Afghanistan. Military officers posted in provincial Afghanistan also spread such ideology, so a thin stratum of both urban and rural Afghan society was exposed to Marxist-Leninist thought.

In 1965, thirty men gathered in the home of journalist Nur Mohammed Taraki, and formed the People’s Democratic Party of Afghanistan, or PDPA. They began to preach Communist theory, and by the late seventies, their influence had grown considerably, especially in the military. By 1978, Daoud was back in power, and he was worried about the growing power of the leftists. So in April of that year, he had all prominent leftist leaders arrested. He wasn’t fast enough, however, and one high-up PDPA member named Hafizullah Amin managed to send his son out with a message to his underground cadre before he was arrested. On April 27th, tanks controlled by the PDPA surrounded the palace, and after a very bloody battle with Daoud’s bodyguards, Daoud was dead and Afghanistan was now under control of the PDPA.

In the aftermath, Taraki (the former journalist) was declared President, party leader, possessor of all the titles that mattered. Hafizullah Amin was his second-in-command, but it became clear that he was the one really running the show. Taraki was a useful figurehead. During their years underground, the PDPA had been formulating “programs” to implement once in power, and so upon taking control they had a complete set of policies, ready to enact—without a single moment’s experience of ever enacting policy.

In theory, many of these policies were progressive, even noble. They outlawed the bride price, for instance, and forbade underage marriages. They declared that literacy classes would be established for women, and that new mothers would receive 270 days of maternity leave.

This only really mattered to those living in cities, not to the majority of the population who still lived in rural villages. But then the PDPA really got the bit between its teeth and tried to reform the countryside. One of the first things they did was cancel all debts owed to landlords by peasants, and outlawed high-interest loans secured by land. In theory, this was a wonderful thing; wealthy landowners had long forced the local poor to near serfdom by lending money at predatory rates. Small farmers who couldn’t afford the interest would lose their land to their powerful neighbors. The PDPA hoped that canceling debts would end this evil practice once and for all.

The problem was, poor villagers and farmers only really borrowed money for two reasons: to pay for a wedding, or to pay for a funeral. And when the regime canceled the debts, wealthy merchants and landowners simply stopped lending money to anyone. Young people could now only afford to get married if they were already rich, and since most weren’t, most couldn’t. This created an ever-rising level of sexual and emotional frustration. Furthermore, only the rich could now afford lavish funerals. Peasant families now had to hold small, meagre events that left them feeling ashamed and humiliated. In the words of Tamim Ansary, “The PDPA wiped out social mechanisms tradition had created to meet the crucial needs of a traditional society without providing new institutions to meet those needs. When things started to go wrong, the feudal lords had no trouble convincing the penniless poor that the regime was attacking their interests, their lives.”

Then they tried their hand at land reform. They declared that no one could own more than sixty hectares (148 acres), and in their first year took eight hundred thousand acres from wealthy landowners and gave it to 132,000 poor families. They also announced they were going to organize one million families into forty-five hundred farming cooperatives over the next year. This went disastrously. In such an arid environment, allocation of water is a crucial part of agriculture, and over the centuries traditional Afghan society had developed an effective network of social roles and traditions that ensured enough water went around. Collectivization striped away this system, grouping people who had never met, had no tribal or ethnic ties, and had no reason to trust one another. This set families in competition with one another for access to water. Some small farmers complained that their plots were getting as little as thirty seconds of water a day. To top it all off, those who received land from redistribution had to cope with the guilt that came with it. Custom and religion told the peasants that this land had been stolen from its “rightful owners” (the feudal lords), and by going against the natural order, they were going to hell. Combine this religious guilt with crop failure and constant infighting, and its not hard to see why land reform was so unpopular with rural Afghanis.

This went on for about a year and a half, the country coming apart at the seams, the regime too busy with coups and countercoups and power grabs and party politics to pay much attention to the countryside. The Soviets stood by, wringing their hands. If Afghanistan crumbled completely, the United States might take advantage of the chaos, swoop in, and create a new ally to replace the one they had lost in Iran. The Soviets could not afford to let that happen. So in late December, 1979, the Soviets invaded with an army of eighty thousand troops, hoping to crush all opposition and quell the unrest with sudden, overwhelming force. It had worked in Czechoslovakia, they reasoned, so it should work in Afghanistan.

It did not work in Afghanistan.

I can go into further detail about the Soviet invasion if you want, but their occupation was less about policy and more about war. Most of the policies the Soviets would have implemented were already in place by the time they invaded.

The information for this answer was taken from Games without Rules: The Often Interrupted History of Afghanistan by Tamim Ansary.