Try playing all the instances of one note name everywhere on your bass. This is not necessarily as easy as you think.
Assuming you have a twenty-four-fret four-string, start with an easy one; play an open E, then the 12th fret, then the 24th fret. Now go on to the A string and play the 7th fret, then ...
Of course, you can approach this exercise in a slightly different angle by requiring yourself to play all these same notes in succession by pitch. In that cse, you would start on the low E and add the octave on the E-string, the same pitch on the 7th fret of the A-string, the same pitch on the 2nd fret of the D-string. Then play the next octave on the 24th fret of the E-string, then the same pitch on the 19th fret of the A-string, the same pitch on the 14th fret of the D-string, the same pitch on the 9th fret of the G-string.
You get the idea. Now pick a different note name... How about F#? It can be harder than you think, but it forces you to know *all* the notes on the bass and is particularly useful for developing a six-string bass style that truly uses the capabilities of your instrument.
Now take some of this knowledge and apply it to unusual melodies.
Try playing melodies and lines where you use no interval smaller than a perfect fifth. This technique can really extend the use of your fingerboard and give you a different perspective on the way you construct lines.
Consider that much of the bass tradition from Bach to Basie involves a bass line with smaller intervalic transitions. Why not turn this on its ear and find the result?
Spend as much time playing this way as you can; I did it for several months once (even in concert...). Once you tire of this method, start adding back the smallest of intervals... So you never play any interval smaller than a perfect fifth, except for a minor second.
That minor second has infinitely more impact because of the large intervals that come before it. Of course, it goes without saying (almost) that note selection and sequence is everything.
[Stuart Mawler@mci.com] [Practice Methods/Tips] [BassWork Index]