A big part of metal soloing is based on the blues. The rest is mostly influenced by classical music, like sweep arpeggios and lightning fast scales.

I really recommend that you start from the roots - the blues. It's very important to learn how to make the guitar sound good, how to make it sing and cry, with just one note.

This is where bends and vibrato make a big difference. A nice vibrato in combination with perfect bends will make any note sound good!