Start at blue. Blue buff is what you need to continue jungling and live. "But what if I get ganked?" Trust me, I know every now and then you WILL get ganked, which is why you get a ward. Set up the ward 1 minute into the game in river so you can tell if someone is trying to catch you off guard. If someone is coming, leave. You might be getting less xp, but so will they. If you have to, get wolves instead and go back to blue at level 2 if you need to. I doubt they'd be there then, and if they are, go get red. If they stick around that long, they are screwing up their own level, and you'll win in the end.

If you manage to get blue, continue jungling in a straight path, and gank mid after you have both red and blue buff. You should be level 3-4, and I generally help mid, but you can help bot if they need it. I find it hard to gank until level 6, but by level 4 you should go back to build Mandred's Razors.

By the time you're level 6, your blue buff should have ran out, but hopefully not your red. Even if it has, and if your jungle is cleared, you should still try to gank. Your ult is perfect for rushing in and helping a teammate if the enemy is pushing. Make sure your allies are ready to run in, and don't initiate foolishly (That's what pings are for). It gets easier to kill your enemy and do more damage once you have Malady, and even easier when you have Wit's end, and even EASIER once you have Mandred's Bloodrazor. Once you have all of those items, your ult will hurt. Hard. Just keep helping teammates push and keep getting kills.

By now, you should be sticking with your team. Make sure the tank initiates first, and if they don't, you should, as you are somewhat tanky. In a team fight, try to ult in on a squishy (This should one shot them, and if not, use your 'q' on them). Now, don't just ult whenever you have the chance; you have to wait at the right time, so you won't be stunned. If you can kill the carry, you will most likely win the teamfight. After that, just auto attack, and use your 'q' when you can. You should deal a good amount of damage and not die, and if you do, use guardian's angel to res.

Also, for your last item, go with Frozen Heart or Banshee's veil. It depends solely on the other team's composition. If they have more AP or CC, get banshee's veil. If they have more AD, get frozen heart (frozen heart is perfect because it gives good armor, mana, and a 20% slow against fighting AD when you hit them).