Counterpoint is very important to raise skills in music composition and improvisation. What method or publication do you suggest?
I suspect that this question might not met the standards of stack exchange in that it would be opinion based. That being said, I looked back at my reading diary (http://don.dream-in-color.net/books/archive.php4?iSubject=83 ) to see what I'd read and thought about books on counterpoint.
I started with Counterpoint: The Polyphonic Style of the Sixteenth Century by Knud Jeppesen and found it helpful, although as I noted in my diary, I found actually performing Palestrina in a choir to be more useful. The next book I read was Counterpoint by Walter Piston which I found more lucid, but it might have been because it was the second book on the topic that I read.