Hey I posted this in the forum probably about a year ago or something, so it's long since been lost to the place of lost threads, but I found it on another forum. Here you go (this is just the basic modes though)
Im going to outline some basic ways to learn your scales, add variety and increase your technique, control, speed and phrasing within scale-learning. But! It will be boring, so you need to make sure you are willing to do it!
LEARNING THE MAJOR SCALE AND IT'S MODES Firstly, i would recommend you go here
Come here...and download chapter one for now. its a pdf file of the tablature from the dvd of John Mclaughlin (one of the greatest guitarists ever IMO). The particular document we will need is in the chapter 1 zip file called 'All Modes'.
Play through this and you will learn the C major scale through two octaves in one position, and then all the subsequent modes of Cmajor. Notice that the second - Dorian - mode is the exact same as the C major scale, just starting and ending on D, the second note of the C major scale. Like the 3 rd mode, the Phyrgian mode is just from E, the third note of the C major scale, to E again. This is all modes are - scales within scales! Its very easy to learn them when you realise this.
At this stage i would recommend making a conscious effort to relate the tablature to the musical score above it, thereby learning the notes on the treble clef. They go like this:
-----F----
-----D----
-----B----
-----G----
-----E----
You can remember this by the mnemonic (i think thats the word!) Every Good Boy Deserves Football. However, for example, G will always remain on the same line of the treble clef stave, regardless of whether it is normal (natural), sharp, or flat. To signify its tonality, it will be prefaced by a '#' for sharp, or a 'b' for flat. This is really straightforward, but confuses a lot of guitarists - still catches me out a lot, im so used to tab!
When you have learnt the notes of the C major scale (C D E F G A B C), you can learn them all over the fretboard and work out scale patterns for yourself, but you should always, always, always start and end your patterns on the root note so you train your ear properly. It is critical to hear the notes of a scale in relation to their root note! Also, be aware that the C major scale can be a little misleading! If you were going to transpose it to an A Major scale, you might think that, as Cmaj is C D E F G A B C then Amaj would be A B C D E F G, but you would be wrong! Notice that the intervals are what is crucial- in the correct C major scale the difference between 3rd and 4th notes (E & F) is a semitone, but in the assumed version of A major we have C & D, a difference of a semitone, meaning our version of A major is incorrect! The formula/ pattern of intervals between notes for any major scale is:
Tone
Tone
Semitone
Tone
Tone
Tone
Semitone
So the correct A major scale would be A, B, C#, D, E, F#, G#, A. A scale of A B C D E F G A would actually be the Aeolian mode of A major (see the downloaded notes!)
PLAYING TECHNIQUE
Firstly, get a metronome-there are many you can download for free online. I use something called Musebook, but i have no idea if its particularly good, it was the only one i downloaded and it has good tempos and time signatures so thats all that matters to me!
Obviously, the most obvious route of learning scales is to increase the speed at which you play them over time, using your metronome to control the speed. A good tip is to record the speed at which you can play the scale, and keep track of your progress. Also, make sure you play on a clean sound, and don't increase the tempo of the metronome til you can actually play it perfectly - dont lie to yourself! its just wasting your time! and also make a conscious effort to use all four fingers to really improve your fretboard ability.
But this is not all you can do. You could play the scale legato (example 1) so that you only pick the first note per string and the rest is all played with hammer ons (ascending through the scale) and pull-offs (descending).
Or you could use scales to practise your alternate picking. In example 2a, i am starting each string on an up pick, followed by a downpick, then an up-pick (hence the 'alternate' picking). In 2b, it is reversed, with me starting on a downpick, then an up-pick, then a down-pick. This really will focus and improve your ability to alternate pick - and learning to start with both up and downpicks will allow you to use the technique a lot more easily. after all, sometimes you aren't always going to be in a position to start with an up-pick, but if you dont know how to pick starting on a down-pick you are going to be screwed!
In example 2c, im mixing the two techiques, playing the first three notes legato then the next three alternate picked, a technique used by people such as Paul Gilbert etc- it can be used to make fast soloing sound a lot more aggressive!
Then we should consider phrasing, and note groupings. In 3a, the notes are played as triplets (three notes per beat), and this is how most people would approach a pattern that has 3 notes per string. But in 3b we are now playing 4 notes per beat (quavers i think), yet exactly the same notes, in the same order. This kind of playing may take you some getting used to if you've never done it before it can be a bit of a head$%. Especially if you play it legato. In 3c, the notes are played as quintuplets (5 notes per beat) which tends to confuse pretty much everyone! Just think of a word with 5 syllables, e.g. hip-po-pot-a-mus or whatever. I've had to refigure the scale here to fit, but obviously you can play it in any order that takes your fancy! Again, play it legato or picked or mixed. Just keep mixing up all the techniques and see what you get! You could play one beat in quintuplets, one in quavers, etc, just push yourself and track your progress with the metronome!
Also, its worth thinking about odd ways to play through your scales, maybe you could skip from the bottom E string to play the next 3 notes on the D string or suchlike? (i forgot to draw an example for this sorry!)
Just be open-minded and constantly mix up all the techniques. And learn it all in all the different keys to push yourself, and let your ears be the guide, when you are feeling confident! And learn all the scales all over the fretboard, not just the ones ive given you. to force yourself to work something out usually means you will learn it a lot better!
Obviously this is all about the major scale, but most rock playing centres on this or the minor pentatonic. To learn other scales just search the web, one place i found was
http://www.cyberfret.com/scales/basic/page2.php but there are many more!
Two more examples ive put at the bottom of the tab concern playing in minor pentatonics (C minor here to be precise!). I mentioned this to berney a while back, instead of playing two-notes per string like most pentatonic scales do (4a), you can push yourself to play 3 notes per string. Its exactly the same notes, same order but it really stretches your fingers.

Thats about all i can think of right now; if there are any mistakes or questions anyone has then please feel free to ask - i was feeling a bit tired today so sorry if its a bit disjointed. hope it helps!
just remember, be creative in learning your scales, you can use them as warm-ups or actual technical practise. Mix up all the different techniques and you'll make good progress!