Me four.
1. Declare the emergency
2. Move troops, Army Corps of Engineers, materiel into place
3. Start building!
4. Expect the democrat-communists to move to impeach in the House. Let them.
5. Expect court challenges. Because only the Congress can nullify the president's declaration of an emergency, push this to the Supreme Court for immediate resolution. That will end all lower-court challenges.
6. Fight, fight, fight, and DON'T back down.
The democrat-communists are THE ENEMY.
Regard them and address them as such.