What can poor nations do to become more wealthy? Their immediate and long term goals should be to increase their gross domestic product (GDP). The more a country produces, the wealthier that country is. To see what poor countries can do to increase their GDP (and what rich countries can do to help poor nations increase their GDP), see The Poverty of Nations: A Sustainable Solution by Asmus and Grudem. See also Wealth, Poverty, and Politics: An International Perspective by Thomas Sowell.
Because of the unique geographic challenges that many poor African nations face, it is doubtful that they can escape from poverty without international assistance. Perhaps the best way the international community can help poor African nations is to improve their transport infrastructure.
For more about Africa and the problems African countries have had since independence, see here.
Many poor countries that have large areas of semi-arid land, can increase their agricultural output simply by adopting better farming practices (see the video below).
But what is the best way to help the poor in the developed world? Is it through the work of individuals, private charities, and religious organisations? Or is it through the government? Or perhaps both?
"The road to hell is paved with good intentions."
Much harm has been done to the poor by those who set out to help them. It is simply not enough to have good intentions; we must look at the results.
Before approaching any government representative, it would be wise to see if such a policy has been implemented elsewhere. What were the consequences of that policy? Did it work in the short term but not in the long term? Perhaps it took a while to see the benefits? Perhaps it never worked and in fact made things worse? (For an example, see here.)
In the book Basic Economics, Thomas Sowell looks at various policies which have been implemented around the world and what effect those policies had, especially on the poor. If you want the government to implement a specific policy, I strongly recommend reading that book first. (Governments must also take into account geography, demographics, and culture when trying to help third world nations. See Wealth, Poverty, and Politics: An International Perspective. To see how a people's culture can either help or hinder economic development, see Sowell's book, Black Rednecks and White Liberals.)