People connect with the raw emotion that can be expressed though a few simple notes. Blues is also a fairly simple style that is based around a few chords. I, IV, V chord progression or 1, 4, 5 basically means there is only 3 chords in a 12 bar blues.
E, A and B chords is one of the most commonly used progression. It is the soloing within the blues though that attracts most people to the genre. The flashy and fast fretboard wizardry that not only looks cool but also sound amazing isn't as hard as you think.
First we will talk about some of the techniques used-
Vibrato- Possibly the most expressive technique, Vibrato is basically the act of bending a string up and down rapidly to create a singing, pulsating sound. Learning vibrato can be tricky at first but soon you will be able to naturally feel it and manipulate the way the notes sound.
Pull offs- This is the act of unfretting a string by letting it go with a slight pluck from your fretting hand thus creating a quick end to a flurry of notes, done well it can add speed to your blues licks.
Hammer ons- The ying to Pull offs yang. The idea of hammer ons is to pick a fretted string then quickly hammer your finger onto another fret without picking. This makes playing fast passages easier without picking every note you play. This will take practice and you will need to build up a little strength in your fretting hand.
Trills- When you combine the two above methods you get what guitarists like to call Trills. Trilling involves hammer ons and pull offs together in quick succession to create a very impressive string of notes. A perfect example of this would be the intro to ACDC's Thunderstruck. It is easiest on the high E string or the thinnest string on your guitar. The idea is to hammer on a note and then quickly pull off. Repeat this at high speed to dazzle your audiences. When mastered you should be able to play lots of licks one handed.
The above are some of the most commonly used lead blues guitar techniques. The thing about the blues is how you express yourself through the notes. It is all about tone and feeling. And tone really is in your fingers, it just takes practice and hard work. A blues master can make a old beat up guitar sing with the tone he has honed through practice.
For a lot more on blues guitar and how to really make it sing visit Best Blues Guitar Tone.