The Budget of the United States Government 2018 titled "America First: A Budget Blueprint to Make America Great Again" is now available online from the Government Printing Office. President Trump recommends increasing defense spending by $54 billion while cutting the budgets of the following departments/agencies: State, EPA, Labor, Education, and Agriculture. He proposes to eliminate both the National Endowment for the Arts and the National Endowment for the Humanities and decrease funding to agencies like the National Institutes of Health and the National Science Foundation which provide money for academic research. Public broadcasting and the arts would also face cuts as would popular domestic programs like home-heating subsidies and clean-water projects. The budget does not address mandatory entitlement programs like Social Security.
If you'd like to see a quick visual representation (graphs and charts) of programs that would lose funding under President Trump's proposed budget, see Bloomberg's March 16, 2017 article "These 80 Programs Would Lose Federal Funding Under Trump’s Proposed Budget."