I think Rawwrh plays Sivir at a silver level. I spent hours with him on it.
So my advice: learn champions in normals, play them in ranked when they are at the level of play as your Sivir.
I had 5 more assists then him, the same amount of kills, and 3 more deaths. The only reason my deaths where higher was because enemy jinx was fed by my support and mid I believe.