You can practice chords all day, but for it to be useful, you have to have a clear understanding of how it all works. It is pretty hard because most of the harmony books out there (some still used in music schools around the world) are absolutely dreary and arid. I can't understand how an author can manage to turn harmony, a subject so rich and interesting--- considering that harmony has a huge part in determining expression, it is the soul of the music, so to speak--- into such a boring read.
There are three books I recommend if you want to study and understand what its all about:
Harmonic Experience: Tonal Harmony from Its Natural Origins to Its Modern Expression - by W. A. Mathieu (this should be required reading in any music school).
Understanding Harmony - by R. L. Jacobs
Any of the books on improvisation and harmony by Emilio Molina, published by IEM.