To win, take LeBlanc mid. After inevitably winning mid lane, try to roam to a different lane that needs your help. Normally jungler should camp bot if they're having trouble, but if he is helping top or playing a farm heavy jungler you can go and gank to help them out. Equally, if top needs ganks do that.
Main points:
- LB will win most mid lane matchups, especially in Silver if you play her right.
- Try to help other lanes if they're in trouble.
- Secure objectives, don't get too caught up on kills especially as LB.
- Help your team as much as possible because LB is insanely good mid-game if she did well early.
If you consistently take objectives, ward the map, and win mid game fights, you guys should snowball a lot and take the game. I definitely wouldn't suggest leaving lane until you pushed enemy T1 unless you absolutely have to.