Ronald Reagan's basic economic plan was to cut taxes and, he hoped, to cut government spending as well. If government spending could not actually be cut, Reagan at least wanted to redirct spending, taking it away from welfare and other domestic programs and putting it towards defense.
The main aspect of Reagan's plan, though, was tax cuts. Reagan believed in an idea called "supply-side economics." This idea holds that tax cuts , especially for the rich and for businesses, will make the economy expand because people will have more of an incentive to work if they have to pay less in the way of taxes. Reagan also believed in the "Laffer Curve," which argues that cutting tax rates will increase tax revenues because people will work more and will therefore pay taxes on a much higher income.
Reagan managed to get Congress to pass major tax cuts. He also got Congress to shift money from domestic spending to defense. These two things constituted the bulk of his economic plan.