Secure the Border with Mexico.
Provide those that wish to Legally Immigrate to the U.S.A. with the required paperwork and procedures to Immigrate to the U.S.A.
Coordinate Efforts with Mexico to stop the flow of Illegal Immigrants through Mexico from the rest of the World. (It's not just Central America Citizens that are using the unsecured Mexican Border as an Illegal Entry Point into the U.S.A.)
For those that have broken the Laws of the U.S.A. and crossed the Mexican border into the U.S.A, hold these folks at locations near the border, process them, and return them to their countries of origin, send a Bill for services rendered to their countries of origin and if not paid, deduct it from any Foreign Aid currently being provided said Country.