Different people learn to play guitar for different reasons. Some what to become rock Gods, some aspire to classic playing and others want to learn to play the blues.
The mistake that many people make however, when it comes to learning blues, is that every lesson should be a blues guitar lesson and this is simply not the case.
The fundamentals of learning guitar are the same, regardless of your genre of music or style of playing. Mastering of the fret board, musical notation, chord structure, all of the fundamentals do not only apply to blues guitar lessons, but all other types of music.
The important thing to remember here is that branching of into playing blues or rock or what ever type you before comes after you have mastered the fundamentals.