Be Lyrical
Starting out by only using chord tones for creating your improvisations promotes a respect for the chord of the moment. As you apply yourself to this strategy with different standards, pay attention to the simplicity of the melodies of those songs to get an idea of where the composer was coming from in terms of respecting the chords. Also, keep your eyes open to specific pieces of those melodies that use only chord tones, as this will provide you with many clues!