When it comes to create a melody, or jam out a lead line do you always find yourself playing the same scale over the same chords or progression. For example, if you have a progression in the key of D Major do you go straight for the D Major scale. It's a common and logical approach but there are alternatives. One of them is known as the relative minor. We'll save the theory for a different day but in short, every Major scale (from which chords are built) has a matching minor scale.
This means that you can play the notes of a minor scale over the Major chord progression so long as you have the correctly matching scale. The chart below shows common keys with the matching minor scale. To use this chart find the key you are currently playing in - let's say the key of A. Compose your lead lines in f#minor. If you are in the key of D compose your lead lines in the key of b minor. This music concept is why you find a lot of guitar players wailing in e minor over a G progression.
There's one more cool thing about this musical concept. It works in reverse too! If you have a song in a minor key you can play the matching Major scale over it. For example, if you are in the key of c#minor you can play an E Major scale over it, or if a chord progression is in a minor you can play a C Major scale over it. Give this a shot next time you're jamming and see if you feel a new blast of freedom and inspiration!