Weaver - max sukuchi, stick & move. learn to last-hit well with the hero (i swear it's not as easy as it looks). Get your linken's up as fast as you can (he really needs the point booster stats and passive for survivability, as well as the perseverance regen for jungle farming). After that, pick a damage item (usually gonna be a deso or mkb) and rush it. Medallion is also a good early choice on him.
Furion - get out of that jungle as early and often as possible as and help with ganks and knocking down towers. As often as possible, have enough mana and treants off cooldown to turn successful ganks into successful tower pushes. Jungling for too long tends to put too much pressure on mid to pull off consistently successful ganks, and it tends to mean some carry the other team is free-farming while nobody on your team likely is. coordinate some tp --> sprout ganks with teammates, get towers, get money. try to not spam the ult because you could accidentally starve your teammates out of farm. Get a Shadow Blade up and running as your first major item for safer pushes. if you see the enemy grouping up as 4 or more and positioning like they want one of your towers, immediately go split push another lane, then tp into any fights to help if appropriate. It may never be appropriate, so in those cases just try to a trade, or to at least force the enemy team to back and defend. Sometimes halting the enemy aggression is what your team needs more than you there trying to help in a skirmish.
I tend to prefer a 1-1-3-1 build @ level 6 for a bit more authority with tower pushes and farming speed, but 1-2-2-1 is also quite good and allows you to tp around the map a little faster. just depends on what your team needs in a given match.
One last thing: carry a tp scroll. It gives you much more freedom. You can tp (W skill) to a lane to push, then use a teleport scroll to come right back and defend a base. Or to pick off a courier then escape for free.
Oh, and if you see Spirit Breaker picked, just don't pick Furion at all. Fuck that shit.
Better players can provide better insight, but that should be a decent start.
http://steamcommunity.com/id/ajreynol
and I don't really have any sort of format for winning items. I just ask people in the channel who needs items. lol. I could come up with something more interesting.