I don't think a wall would help. We need effective, positive action if the immigration issue is to be solved without stepping on the freedoms we aim to uphold, or soiling relations with our neighboring countries. My thought is to allow law enforcement to track down illegals - possibly even open up a temporary branch of government employment to work directly on the problem in order to minimize problems (like a more humanitarian form of the FBI) - and incarcerate and deport harsh criminal elements.
Illegals who have otherwise committed no serious crimes would be issued a license detailing a reasonable quota of money owed to the local government at a low interest rate, which would only become active once they are employed. They would also have to have at least one family member studying towards American citizenship (even if it's just a study guide at home). At the end of the afore-mentioned quota being fulfilled, they can be issued with a citizenship test.* If the test is completed, the interest would no longer apply, and the family/individuals would be given the full rights of American citizens. If the test is failed, the interest is simply renewed and the family/individuals may continue to work at it.
*Families that request and complete the test as a whole may be removed immediately from the tax, and granted citizenship.
Any thoughts on how that might work? I know there are some grey areas (what about an elderly couple that finds it too difficult to study?) but those could even be solved on a case-by-case basis. There's also the fact that people might simply not want to pay such a tax regardless of its reasonability- to which I'd respond that they are not U.S. citizens and are therefore not protected by the Constitution - in which case such people would also be deported.