Are you tired of playing up and down major scales and natural minor scales? Here's something to try: the melodic minor scale. Never heard of it? Then this quick tip is for you.

1. Construction of the Melodic Minor Scale

As the name suggests, the melodic minor scale sounds like a minor scale. This is our starting point: a minor scale has a minor third in its formula. I also like to think about this scale as a variation of a natural minor scale. The melodic minor scale is not the only variation, but it's a strong variation.

Here's the formula:

As you can see, we raise the sixth and the seventh. The result is a more balanced sound, with a push towards the octave. I like to think of it as a combination of Dorian and harmonic minor, if you've ever dealt with those scales.

As you can see, we ascend the scale with the previous formula, but descend playing a natural minor. We have this split formula because it was thought that melodic minor would have been played on the tension chord (V7) to have a nice release on the I chord (Im). Nowadays the use of this scale goes way beyond this rule, so I suggest you think it as just one-way formula: a minor scale with a raised sixth and seventh.

2. Fingering of the Melodic Minor Scale

Here is how you finger the melodic minor scale.

You may have noticed, some fingerings have four notes on the same string. This requires a position slide or a big finger stretch.

3. Application of Melodic Minor Modes

Like the major scale (Aeolian), the melodic minor minor has its own modes too. (See this PDF file.)

The most-used are the Lydian Dominant (also called Lydian b7 in some contexts), and the altered scale (also called Super Locrian). If your time is limited, start with those.

Speaking of application, why and where would you play melodic minor? First of all, you can play it over every chord that contains notes from the melodic minor scale, no exceptions. (This applies to every scale you know.)

That being said there are multiple clichés that use this scale:

• The first would be on V7 resolving to the Im. In this case, you play the seventh mode of the melodic minor scale, Altered.
• Or, you may play this scale over a Dorian progression—for example Im-IIm. Since there's no seventh involved, you can decide whether to play Dorian or melodic minor. 
• You can also play it on a MinMaj7 chord, even though you don't come across one very often.

You can also play melodic minor over a natural minor chord. Why? To spicy it up a bit, or to sound more interesting. Don't get me wrong. I don't think that playing a natural minor scale is boring. At the end of the day, you just have to make your scale sound good, no matter which one you're playing. And above all, you have to play something that fits the context of the music.

In this audio example I played melodic minor phrases over a Im-IIm progression. I could have played Dorian, but let's see if you like this better.

Conclusion

What are you waiting for? Raise you're sixth and seventh degrees, and give a bit of balance and exotic tone to this minor tragic universe!