Many conservative think tanks are well known and seem to be well funded. They have different goals, such as libertarianism (Cato) or neo-conservatism (New American Century). Here is basic information based mainly on their we sites.
The American Enterprise Institute (AEI), headquartered in Washington, DC, conducts research on economic, national defense, foreign policy and other items broadly defined as public policy. Its 2016 Annual Report stressed "expanding liberty, increasing opportunity, and strengthening free enterprise." Photos of Republican politicians were prominently displayed on their site.
The Cato Institute, also in DC, is a libertarian think tank, founded initially as the Charles Koch Foundation (which indicates the basic funding source and perspective). Downsizing the federal government is a particular focus. It also stressed "individual liberty, limited government, free markets and peace."
The Heritage Foundation (DC) does public policy research to "formulate and promote conservative public policies based on free enterprise, limited government, individual freedom, trade, values, and strong national defense." With business support (such as the Coors family) it promotes free trade and globalism. Its website encourages us to "join the fight to drain the swamp," apparently referring to the other lobbying groups.
The Hoover Institution, named after Herbert Hoover and located at Stanford University favors: "representative government, private enterprise, peace, personal freedom, and safeguards of the American system."
The Manhattan institution, established in New York City, focuses on domestic policy and urban affairs--"greater economic choice and individual responsibility." It pushed supply side economics in the Reagan era.