Generally:

• Signs on private property require permits and must meet size, type and location requirements of Chapter 33 (Zoning Code)
• Signs are not allowed to be placed on the public right-of-way.
  (Sec.33-95)
• For general questions consult your local Team Metro Office
• Signs require a Zoning Improvement Permit (ZIP) and possible building permit
• All of these permit applications are available from the Miami-Dade County Building Department:
  • 11805 SW 26th Street
    Off Coral Way (SW 24 Street) and the Florida Turnpike
• Zoning code questions call (305) 375-1806

See the Section cited above of the Miami-Dade County Code for full text.