The third variation of the blues guitar scale might be a little intimidating at first, as it spans six frets. However, if you take a look at each line, the only real tricky part is the first string (the thinnest one). It's five different notes, so you'll have to move your hand up at least one time.
For a more comprehensive list, check out the Blues Guitar Scales Master List.
Here's the diagram.
Speed won't mix well with this scale at first, unless you've established a fair amount of quickness on the fretboard already. For a little help you can consult this article on increasing dexterity. Otherwise, just take it one line at a time, and as slow as you can tolerate. If you're getting buzzing notes, you're going too fast.
Increasing Hand and Finger Strength
Increasing Dexterity and Range the C Major Guitar Scale
Blues Variation One
Blues Variation Two