While there are a few variations of the blues scale, the most common is the minor pentatonic scale with the addition of a flatted fourth note. In the simple key of C, this scale is C, Eb, F, F# (or Gb), G, Bb. Learn this scale and its pattern in the key of C, then apply it to other keys simply by maintaining the pattern and starting on a different note. This will allow you to play this blues scale in any key.
The walking bass is a rhythm pattern played with the left hand and the bass notes of the piano. A walking bass line consists of even rhythm notes played successively and repeated again and again beneath a 12-bar blues progression (the "meat and potatoes" of the blues). This pattern is so named because it creates a walking effect. It is one of the primary rhythm figures in blues, and playing it correctly will make you sound as if you've been playing the blues for years.
The 12-bar blues progression consists of 12 bars of music repeated over and over. A 12-bar blues consists of four bars of the first chord, two bars of the fourth chord, two bars of the first chord, one bar of the fifth chord, one bar of the fourth chord and two bars of the first chord. The Roman numerals indicate the chord position, but the names of the chords change depending on the key you play in. The key of C, for instance, contains these chords: C, F, C, G, F and C. A seventh is usually added to make these chords seventh chords. This is the pattern you would play with your right hand.
Use the key of C to get familiar with the pattern and progression. Play a walking bass with your left hand while doing the 12-bar chord progression with your right hand. The combination of the two will instantly make you sound as if you've lived a hard life.