start a tune of your own in any key. Play a Major chord and just make up a melody starting from a note.Start from the same note and now play a minor chord and see how your melody deviates. Now do the same with a dominant or seventh chord. These variations are what these different family of chords make you do.Training your ear to atleast hear the different families,major,minor and dominant is a must to be able to phrase well and make stuff up.