Not Updated For Current Season
I'm just going to explain my jungle pattern as this is defining difference in my build and play style. Also I want to credit Simple Logic for creating his guide, which quickly helped me own with Nunu.
1.Start with 2 golems, smite and consume one immediately then run away so you can wait a few seconds for your consume cooldown (This will allow you to be nearly fully hp as you head to the next group of creep). Once cooldown on consume is at around 8 seconds begining attacking the 2nd golem and consume once it reaches below 500hp.
2.Proceed over to 3 wolves consume the brown and ice the blue wolf simultaneously.Finish the brown wolf and the 2 remaining wolves: KEY TIIMING with the 3rd wolf is you don't want to use frost blast on him as you'll need the mana on the blue golem. You want to use your first health potion just as you finish the last wolf since Consume on the blue golem will put you at just about full hp.
3. Consume blue golem, spam frost blast 2-3 times, smite and your on your way. Move on to healer creeps then red, and proceed to ganking and follow the build --> Rest will be downhill from here.
"WHY DON'T YOU START AT BLUE FIRST???" -- you may hear people say this, just nicely say it's safer, and they'll be quiet once you start ganking and owning.
**For those who wonder about the creep pattern, it's much safer than getting ganked at blue where many people expect nunu to be first. If you decide your really want to start blue first, then a little tip: consume a blue wolf first as that creep camp will spawn about 15 seconds before the blue golem.
**If I get comments or questions I will elaborate. There are many fine details you can tweak in your play style such as going 3 consume and 2 frost blast to start so you can jungle faster and have dragon killing power. If you go ghost you don't need blood boil to gank early, but it's nice to have the blood boil level 1 if you plan to roam a lot. Enjoy!