I'm not quite sure what the question is, but...
For ska, you might want to practice some walking lines, like in Jazz music. They tend to have lots of those.
ALL scales you will run into have a 1 (root) and 8 (octave) in them, and most have some sort of 5 (whether it be natural, flat, or sharp).
That said, you should work on your triads. You will probably only need major and minor, and MAYBE diminished. A triad is a chord built on the 1,3 and 5. For this exercise, we'll throw the octave in there (called a 1, for this).
Major: 1-3-5-1
Minor: 1-b3-5-1
Diminished: 1-b3-b5-1
What you'll do is simply arpeggiate them, then invert. Like this:
1-3-5-1, 3-5-1-3, 5-1-3-5, 1-3-5-1. You will land two octaves above the lowest note. In C, it'll look like this:
C-E-G-C, E-G-C-E, G-C-E-G, C-E-G-C.
Most ska lines are built off of those, so try that. For the walking lines, try to use some of the notes in the chord you are playing over (in case that wasnt obvious!). I.E., use b3's and b7's over a minor chord, not 3's or 7's. You COULD, but it'll sound pretty weird.
Regardless, most lines are built of walking and triads, so that will give you a good base to start of off. I hope this helps.