faulty damper is very right. It's an easy and quite good method to learn counterpoint. You will get the idea as soon as you already know which notes sound good together, so you can focus on the line and not only on the harmony. Of course, good is relative and you may find dissonance much more interesting than consonance...or a mix of both. The more freely you define harmony, the more liberties you will have with the line, but it can also be very interesting to set yourself the limitations of tonality or even a medieval kind of tonality where you stay very close to the tonic at all times. Or a type of counterpoint where octaves, fifths, fourths and sevenths are the primary intervals... Experiment with it and you will find a whole new universe outside of the ..."standard" homophonic ways. Never forget, however, that you can only be good at polyphony if you understand it's homophonic aspect. Or, with other words, always keep track of the overall idea that actually holds your lines together.