Freedom is the most important factor in a thriving economy. The government's regulation of just about every aspect of running a business, as is common in America today, is a form of fascism.
All government licensing of professions should be repealed, from medicine, to plumbing, to child care. Licensing is simply a way for the State to extract more money from people, money which could have been saved, invested or spent in other ways. Voluntary organizations comprised of those in the profession should offer certification, if certification is desired. All government permits and regulations surrounding building should also be repealed, as this raises the cost of housing and running a business, because costs are always tacked on to the finished product.
Zoning laws should be highly curtailed or repealed altogether. People should be able to run businesses from their homes, or sell things out of handcarts if they so choose. Selling in that manner was extremely common in the late 19th and early 20th centuries, and the descendants of those people (Jews, Italians, Irish) are now firmly established as the middle class.
Trade barriers should be abolished. People should be able to buy, sell or establish business relations in any country, without having to deal with tariffs or other protectionist measures. Foreign aid should be stopped, being replaced with capital investment in developing countries, which can certainly include charitable organizations who seek to offer loans so that people can start their own cottage industries
Minimum wage laws should be abolished, as should child labor laws. In this age of new vistas in education, namely homeschooling, young people who are not academically inclined should be free to go to work, to apprentice, etc. Both minimum wage laws and child labor laws prevent this. Social security taxes and medicare taxes should also be abolished. Employers and employees should contract together to determine wages and benefits.
Socialistic, paternalistic, government programs should be abolished. All welfare programs, the government school system, the National Endowment for the Arts, the FDA (and the list would go well beyond 1500 words). All this is money that has been stolen from productive individuals and put into supporting huge bureaucracies, in addition to squelching individual/family/church initiative in caring for the poor, in education, and in private philanthropy. Of course, this means that taxes should be slashed to the absolute minimum, including taxes on businesses, on personal income, on sales, on inheritance, and the list could go on.
Immigration laws should be repealed, except perhaps to require health screening. With no welfare state in place, immigrants are a blessing to a country as they contribute to the economy by working and by purchasing goods here.
Government subsidies of every kind should be abolished, as should price controls of every kind. Interference like this hampers the working of the market by distorting the information about supply and demand, resulting in shortages or surpluses.
Although I don't understand it very well, I do know from my limited reading that the expansion of the money supply increases inflation, and our government is printing money 24/7. A return to a sound money system of some kind, which very well may be a free market in currency rather than government monopoly, is necessary to decrease inflation.
Political, personal and religious freedom is also a necessity for a thriving economy. The American experience contrasted with the Socialist/Communist nightmare illustrates this. When people are not seen as individuals who stand and/or fall on their own merit and initiative, but rather as cogs in the State machinery, they lose incentive to be productive in all arenas of life because they know that their money will be stolen, their speech curtailed, their exercise of religion restricted. Of course, a black market always pops up in these situations, which is then the cause of increased taxation to provide police to repress it.
Regarding environmental concern, there have always been environmental problems. Before the automobile, city streets were covered with horse droppings. People used to bathe, wash, drink and throw trash into the same rivers. The free market will provide some solutions to environmental problems as people desire solutions and innovate to achieve means to increase productivity while protecting resources. The best way to do this is to enforce private property rights. If someone, for example, needs wood for their business and takes it from their own land, the incentive not to deforest is great, as their livelihood depends on those trees. Read about "the Tragedy of the Commons" (a quick google search) to see what happens to common land and resources.
I will end by saying that this is not a perfect world, and there are no perfect people. Greed exists, exploitation exists, etc., but regulation by government does nothing to change this fact, and there is every evidence that when economic decisions and control fall into the hands of the State that totalitarianism follows. It is my belief that freedom and private property (coupled hopefully with Christian ethics) is the best opportunity for the most thriving society and economy that we can expect to see in a fallen world.