#1
hey guys,
i've been playing guitar for about 16 months now, i've been practising technique a lot, i learned lots of songs, chords and stuff. but i think it's about time that i move on.

i wanna learn how to improvise when soloing. so yesterday i was jammin with a buddy of mine who's quite good at it, so he asked me to improvise in C major scale but erm.., i've never payed attention sofar on which notes i play when i play something. so, could you help me up please?

the question is, where do i start?
#2
learn your scales duh :-P here...go here and have some fun

www.all-guitar-chords.com and pull out the specific scales u need. I suggest learning your major scales obviously, but in multiple ways; learn ionian as well as phrygian and locrian if u can (it'll help w/ your knowledge of the scale). Practice these scales obviously for at least a few weeks and then start coming up w/ melodies using only those notes within that scale...you'll suck at first but you'll get better (this is sorta the brute force method to it...but i guess if u want a lesson in theory on this subject just ask and ill post...just it'll be really long)
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#3
Sure. Basically what you should do when first starting to improvise is start with a simple scale, for example, the pentatonic. It only has 5 notes so it's easier to remember. Now, learn all the note positions on the neck in the key you want to play in. So for example, if you want to play in C major using the pentatonic, learn all the notes in that scale in key of C major on the neck.

Then just start practicing jamming over a couple backing tracks in the same key. Another good thing to do is learn the chords that fit each key too.
Hope this helps.