Second only to soloing (improvisation), no subject is more feared or misunderstood by students than walking lines. It seems that they feel it is an advanced skill that they are either not ready for or is not applicable to them because it is just for playing jazz. While it is MOST prevalent in jazz, it is also present in other styles and proficiency in walking lines will aid in all aspects of playing.
Ok, you may ask...how?
Well, walking lines require the ability to "think ahead" in your playing. You need to know where you are and where you need to go so the walk remains coherent. You also have to be proficient in the notes/arpeggios/scales of the cords in order to apply them creatively. It is not rocket science to realize that this skill has the potential to make you a better player no matter what the style, level or instrument.
So how do you get started with walking lines?
Consider the following progression:
| G | C | D | G | Am | D | G | D |
Playing just half notes, construct a "2 feel" bassline where each bar consists of the root of the chord and a note that leads to the root of the next chord. The second note can be a chord tone, scale tone or chromatic and your choice can vary from chord to chord. They can also theoretically be of any pitch. Doing this gives the bassline more of a varied feel or "breath". If you don't know how to write in notation, use whatever method you are comfortable with (tabs, letters, etc.)
For example: G-B, C-C#, D-A, G-D, A-D#, D-F#, G-E, D-D.
The first bar (G), I used a chord tone (B)
The second bar (C), I used a chromatic (C#)
The third bar (D), I used a chord tone (A)
The fourth bar (G), I used a chord tone (D)
The fifth bar (Am), I used a chromatic (D#)
The sixth bar (D), I used a chord tone (F#)
The seventh bar (G) I used a scale tone (E)
The eight bar (D), I used the root (D)
Of course, there are many ways to construct this bassline. You should explore all the possibilities. Understand that your bassline should be approached as a "whole unit", not just a series of notes. The ups and downs, skips, etc. all add to the line's interest and musicality. Play your bassline along with someone playing the chords to hear the colors it creates and how it moves the harmony. Remember, your job is to make a line that defines the chords and there is a fine line between and interesting line and an ambiguous one. As you get better at these lines, you can experiment with using another chord tone as the first note instead of the root. This is more difficult and is not appropriate in all situations as it can conflict with soloists, vocalists, etc.
Once you are comfortable with the "2 feel", you can move on to a walk. This is, of course, a quarter note melody that follows the chords. Now, the walk need not always consist of different notes. Many students make this mistake. Doubling notes, sequences, octave splits, etc. give the walk interest. To start, you can use the "2 feel" as a template. The two notes in each bar of the “2feel” can be used as the first and 4th notes of your walk.
For example, from the first bar of the “2 feel”:
G-B becomes G-D-G-B, etc.
The next step would be to make a "2 feel" and a walk over a tune. You can use a jazz standard or any tune which you have the chords. Write out a few, making each subsequent pass more "adventurous". In theory, when you play a walking line, it is supposed to be slightly different every time you come back to the top of the chord sequence.
The last thing you can do is put a rhythm or groove to the line. That is, replace the quarter note rhythm with another. This will take it out of the jazz idiom and make it applicable to other styles.
So, you can see studying how to construct walking lines goes beyond the skill itself. Once you are on the way to mastering the "looking forward" concept, your ideas will be much easier to translate to the fingerboard.
Lots of luck!
Message me with questions!