As far as sweeping goes muting the strings can occur with both hands either way. You can do the same method as you would for tapping when sweeping which involves palm muting the strings you aren't playing at the time so after. Or you can work on placing the fingers of your left hand down in a way that mutes the strign above and below whatever position you are in. Basically that entails placing your fingers on your lef thand down in a way that uses the tip to mute the string above the string you want to play on and leaning it down so you mute the string below it.
Or you can do an insane playing technique I use every once in a while that uses your pointer finger on my left hand to mute all the strings above my ring finger while playing slow stuff. Makes it sound a lot better, the other technique using your right hand to palm mute is similar and does the same thing by muting the strings you aren't strumming.
Another cheap ass technique lots of people use such as Malmsteen, is tweaking with pikcup selection and the volume knobs while playing their solos. This takes quite a bit of practice to coordinate and you should probably not experiment with switing during a solo unless you have complete control over your playing. Adjusting the volume of a sustained note during a slow solo can make it sound much better. Also switching pickups for slow and fast parts can also be a cool effect, as the neck pickup is usually better for a smooth sound, and the brigde is better for fast twangy tone.
Legato technique basically entails being able to hammer and pull-off an entire run making it sound excessively smooth and fluid.
On shredding though, you should choose 5 or 6 insane guitar solos to learn. As most people will tell you, practice slowly and build accuracy and speed. The solo's on the Four Horsemen are decent for a beginner to practice.
Hell anything off Metallica's first album is good beginner practice, it's practically the same **** all the way through...hope that helps in any way
- Enjoy