First, we have to realize that we really do not know for certain what sorts of policies are likely to help countries develop economically. If we knew for certain, there would most likely be fewer countries that are less developed. People disagree on this topic largely as a result of their political philosophies.
Most economists and government officials in the developed world believe that countries need to open their economies in order for them to develop. They believe that free markets are the best way to achieve economic growth. This means, for example, that they believe that developing countries need to adopt free trade policies. It also means that they need to reduce the level of government intervention that they have in their economies. This could mean that governments should not own companies in the way that Mexico owns its national oil company, PEMEX. It could mean that governments should have fewer laws that make it harder for small businesses to open and to hire people. Developed world economists believe that these sorts of policies are likely to bring about economic development while their opposites (less free trade, more government regulation) are likely to undermine the cause of development.
Of course, there are many people who believe the opposite. These are people like leftist social scientists and people from developing countries. They believe that the free market policies described above are simply tools of the developed world. These policies, they believe, are aimed at keeping the developing countries subordinated to the richer countries. They would advocate more protectionism and perhaps more government control of their economies.
One thing that most people can agree on is that developing countries need better infrastructure and more honest government. These countries need to have good roads to move goods. They need reliable water and electric supplies. They also need to have governments that will actually obey the rule of law rather than engaging in corrupt practices simply to line their own pockets.
Thus, there is no clear consensus about what policies are conducive to promoting economic development. People can have different views on this issue depending on their political philosophies.