If you are playing solos ditch that and play rhythm accomiment. Take the fake chord sheet music you used with the guitar and play the chords root note to the beat of the song. Same as you did on the guitar, but this time you are not strumming the beat you play notes of the active chord to the beat. Just roots for now -- we will go deeper later. See what you can do with this.
Little more -- you are on the root and want more than just roots in your bass line......
The 5th of any root is up a string and toward the bridge two frets.
The 8th of any root is up two strings and toward the bridge two frets - right over the 5.
The 3rd of any root is up a string and back a fret.
The 6th of any root is up two strings and back a fret - right over the 3.
The 7th of any root is up two strings and over one fret.
I'm not going to speak about the 2 and 4 as most chord tones do not have the 2 or 4 in them. Sus and add 4 chords will use the 2 & 4 and I don't run up on them that much in the music I play. So if you are following the chords and if you know where the root is the 5, 8, correct 3 (3 or b3), correct 7 (7 or b7) and 6 will play a bunch of bass lines.
R-5
R-5-8-5
R-3-5-7
R-3-5-6
R-3-5-8 any combination of those notes in any order will work.
Yes pick the groove notes that work best with this specific song - rhythm has more to do with accompaniment bass than specific notes... You can groove roots. If you need more help yourself to the above.
Now melody. The major pentatonic scale has been used in a zillion tunes. It's made of the R-2-3-5-6-8 notes. I have not mentioned where we find the 2. The 2 is same string as the root and over two frets toward the bridge. Mix and match and see what you can do. The minor pentatonic notes are R-b3-4-5-b7. Like the 2 I have not mentioned where we find the 4. The 4 is up a string from the root, same fret. If the tonic chord is major use the major pentatonic, and if the tonic chord is minor use the minor pentatonic.
Composing - three close notes then a leap of at least a 3rd
is one way to build a melody. From where you landed, do it again - three close notes then a leap. Remember to include pauses, rests, etc. so the tune you have composed can breath.
Playing melody of the tune. Listen and echo the melody, one phrase after another. Take it one phrase at a time.
- Mary had a little lamb,
- little lamb, little lamb.
- Mary had a little lamb,
- It's fleese was white as snow.
That four line head will probably repeat itself through out the tune.
Have fun.