1st you should follow the CCNA wireless course 2nd take the exam should be 640-722 IUWNE
3rd you have to make sure to work with cisco wireless devices in both autonomous systems and lightweight solutions to gain experience.
4th you have to make sure to have knowledge about radio waves ,bands, wave distortion, digital modulation ,interferences ...etc. the course will not give you all information’s about digital communications fundamentals you should find these information’s yourself.
if you follow this pulse practices and gain experience you will be Wireless network specialist and keep upgrade yourself to the next level CCNP wireless