I'm not sure where to go and what to do when it comes to improvising. I know a fair amount of scales and guitar techniques and yet my improvisations all sound very...'pentatonic'. That is a very arbitrary adjective so I'll explain what I mean. I can be using exotic and interesting scales with many guitar techniques such as legato runs, pick sweeps, arpeggios etc. and yet it still sounds similar to the sort of way a beginner improvises using the pentatonic minor and simple ascending and descending patterns. My question is, how can I make my improvising sing? If I'm doing some samba solo, I need it to be really melodic and beautiful but I'm unsure of how I would achieve that. Any advice?
It's funny that you tagged this question in 'technique', because that's obviously not your problem. I think your technique is far ahead of your ears. Once you learn advanced techniques, that involve fast playing, it's hard to go back and improvise slowly, note by note. But that's what you need to do in my opinion. Get some ear training software (like this one), and practice on it once or twice every day (before you pick up your guitar for example) for 10 to 15 minutes.
The other exercise I would recommend is to play (improvise on) guitar and sing the notes without plucking the strings, then replay the same thing normally to make sure you got it right. I play guitar and trumpet, and since the trumpet is so loud, I often sing instead of actually blowing the notes. This is my favorite exercise, and sometimes I enjoy it more than actually playing. The key is to improvise slowly (if you want you can sing faster and not guess all the notes as long as you can guess the strong ones (strong beat/long duration)). You'll immediately notice that the improvisations you sing are very different from the ones you're used to improvising on guitar, because the guitar forces you to think in patterns and sequences that you are used to playing, because you're under the pressure of constantly delivering fast and flashy ideas. This is why people often end up running randomly up and down the scale not really getting what they want. I can improvise pretty fast if I'm told to, but I would much rather play the simplest and slowest things so my ears can keep up, this is when I really feel that I'm creating spontaneous music and expressing myself.