Lets start with a little history on the roots of blues. Memphis blues, made famous by the two Kings, B.B.King and Albert King. This B.B. King lick is one every blues guitarist should know.
e|-------8-------------|11-10-8------------------------|
B|------8--11-8-------8|-------11-10-8-----------------|
G|---8h9-------11-10-8-|--------------11-10-8h9--------|
D|---------------------|-----------------------10--8-10|
A|---------------------|-------------------------10----|
E|---------------------|-------------------------------|
Source: 101 Must Know Blues Licks by Wolf Marshall
(This is a great book, and you should get it. It's got tons of blues licks that are really awesome, from the 30's to present).
Now, theres a difference from playing blues right off a page, and really playing blues. Add a few bends, slow parts up, speed parts up, Blues is infinitely changeable, but don't forget to add style to it.
We have a basic blues riff in, now lets go to a harder one
E|------------------------------------------------------------------15-15-15|
B|-----------3---5--3-------5-5-----------------8----10--8----------15-15-15|
G|-----------3h4-5--4-------4-4----------7--10--8h9--10--8h9--------15-15-15|
D|-----2--5------------5----5-5----7/10----------------------9--------------|
A|--5-----------------------------------------------------------------------|
E|--------------------------------------------------------------------------|
This is the intro to "Texas Flood" by Stevie Ray Vaughan. It's played a half step down! But still sounds good regular tuned too.
Its a pretty good piece of blues but you need to listen to it to get the full rhythm of it. Here is a link to listen to it.
Now a really good blues scale to learn is A minor Pentatonic
e|-------------------------5--8|
B|--------------------5--8-----|
G|---------------5--7----------|
D|----------5--7---------------|
A|-----5--7--------------------|
E|5--8-------------------------|
Its a pretty basic blues scale thats easy to learn and master
Now try and create your own riff from this scale
Some more songs you may want to learn are Hey Joe by Jimi Hendrix and Little Wing by SRV they are fun songs to play and will help develop you blues playing.
Now you may think, why do I need to learn the Blues? Well son, the blues is what I would call the roots of music. From it spawned country and Rock N' Roll, from Rock, grunge, and from that, Metal. So as you can see, blues is the beginning of all music from guitars. So, if you want to master the instrument, go back the basics, and from there go forth.
Now If there are any specific questions, or anything you want me to post a guide on, comment and I will get back to you as soon as possible.
e|-----5--8|
B|-----5--8-----|
G|-----5--7-8-----|
D|-----5--7-----|
A|-----5-6-7-----|
E|5--8-----|
[/c ode]
I always learned this as the blues scale and what you posted as the pentatonic scale....
this is almost all wrong, guitars existed before blues first of all... I don't know if you recall there is such a things as classical guitar so if you want to start from the roots, that would be where to start.
second thing that is wrong is your time line of "...rock then grunge then metal" metal began in the late 60's in the UK, and grunge began in washington state in the mid 80's.... grunge was actually a combination of metals idea of being heavy and the classic rock idea of letting notes ring long enough to "feel" them...
the only other things is I'm wondering why you didn't start with 12bar blues? I mean it is the easiest way to get the blues feel, and if you listen there is usually some variation used in almost every blues song....