Playing blues guitar with Ernie Ball strings can be a lot of fun and very musically pleasing.  The difference between Blues and classical is that classical is based on the diatonic harmony, where the I, IV, and V chords are major and only the dominant 7th chord in a key is on the V chord.  However in the blues, every major chord can be a dominant 7th chord (the I, the IV, and the V).  The basic twelve-bar blues progression is usually composed entirely of 7th chords.

A twelve-bar blues is a specific chord progression that can be played in any key.  The way it works is very simple.  The rhythm is played using I, IV, V chord progression.  Simply put you play I as the root then move to IV, keep this up for eight bars then on 9th you move to V then IV then I and finally V.  There are different variations of it but that's the basics of it.  Literally thousands of songs have been created using the twelve bar blues form.  They may have different tempos or rhythm, but the basic structure is the same.

Another trick is left hand muting.  Left hand muting is done by releasing the pressure on the note, as soon as you play it,  but keeping your finger on the string so that it dampened the sound.  This makes the note shorter then notated, or staccato.  This is not to be confused with palm muting  where you rest the fleshy part of your right hand palm lightly where the lower strings meet the bridge of the guitar.

Lastly you should know and understand phrasing.  This is the length and timing of what you play.  A music phrase can be long or short, relaxed or hurried, smooth or disrupted, just like a spoken phrase.  Phrases are smallest unit of improvising.  They mostly are grouped with there rhythmic similarities.  Some of the best blues playing is based on the very simple idea of playing a phrase, then repeating it and adding to it or changing it a little.