What are the effects of constant chanting, and how should it be done?
Constant chanting will get us constant service to Krishna, and constant service to Krishna will get us constant chanting!
Chanting doesn't just mean japa, our private meditation, but rather glorifying the Lord and His name at every moment with our mind, speech and actions. And it should be done in every way possible—hearing, chanting, remembering, serving the Lord and His devotees, and taking full shelter of the Lord with our every endeavor.
Of course, these things happen gradually. But one begins by chanting regularly each day, doing some service for the Lord and His devotees, honoring food offered to the Lord, and reading shastra like the Bhagavad-gita and Srimad-Bhagavatam. All these things will support our ability and desire to chant. Gradually we will develop a strong desire to chant, which will in turn allow us to keep the holy name of Krishna in our mind and heart all the time.
I hope this is helpful.