The federal government has passed repeated amnesties with promises of securing our borders going forward. It is past time to live up to these promises. The most effective way to discourage most illegals from entering the country is to remove the magnets (e.g. employment, social services, free/discounted education, anchor baby chain migration, ... ) that draw them here. This country has now matured and does not need the massive immigration it once depended on.
Illegal immigrants let employers pay low-ball wages. This discourages many of our own from looking for work. This puts a further burden on our social services, and promotes dependency on welfare.
Most illegal immigrants are industrious. It is exactly these people their own countries need to improve life there.