I am aware of the lack of information in this guide. I know, I have found jhoijhoi's awesome Guide-how-to-guide
I will adjust my guide accordingly and add various sections, etc.

Morning, you LoL-folk out there!
This is my first Mobafire build guide! And, as it turns out this might not be my last. I will try to keep you updated on me, myself, Amumu and this guide.

I have published this guide already, so people can give feedback and I can adjust this, along with my other adjustments to the guide. Enjoy!

Why do I take these runes?
- Ability Power: for that extra bit of damage to start off with in the jungle. Without an pull or extra damage on the golem, you can clear out the jungle fairly easy at the first levels.
- Cooldown reduction: more skills in less time: always good to have!
- Magic penetration: same for the AP; that extra bit of damage when ganking and in the jungle.
- Armor: Armor is always a good choice when jungling.

Why do I take this skill sequence?
I start with Tantrum, because it has a faster and higher damage output than Despair. It helps clear the jungle much faster than when starting with Despair. That's also why I max out Tantrum first. After that, maxing Bandage Toss is the best way to go. There are a few reasons: 1: Because of the extra damage it provides when ganking. 2: The cooldown is reduced from 16 seconds at level 1 to 8 seconds at level 5. This means: more stuns, better ganks, just plain awesome. I max out Despair last.

I'm still in doubt if I should change the Ability Power masteries to the utility masteries with the extra buff duration. I will get back to you on this.

STARTING ITEMS
5x Health Potion and Hunter's Machete. These items are just best to start with for every jungler out there. Use it...and use it well!

FIRST RETURN
After clearing out the jungle and a possibly succesful gank, you can buy the Spirit Stone. This provides health regen and mana regen, making Amumu less blue dependant as he already is. (Also, this means you will not need to buy a Philosopher's Stone to prevent mana regen problems.) If you can buy Boots, go for it. If not, take one or two Health Potion and a sight ward or two in order to control the map.

EARLY GAME FOCUS
I prioritize the Spirit of the Ancient Golem first. Why? It gives you a decent defensive boost with health and armor, also the extra jungle stats are nice AND, last but not least, the Tenacity! This allows you to purchase Boots of Swiftness, rather than Mercury's Treads. Meaning you stick to your champions and never let them go because the next prioritized item is, after your Boots of Swiftness, Rylai's Crystal Scepter. This item gives you health and ability power, and if you enable Despair in teamfights, people around you are slowed all the time. This is awesome in chases. If you pop your ulti, other champions around you are slowed when they can move again.

MID- TO ENDGAME
At this point in the game, I check out the opposing team. Do they have a fed AD or are they highly dependant on AD damage, then I take armor with health: Sunfire Aegis. If they have a fed AP or mostly AP damage, then I take an Abyssal Mask. If you really need to boost your magic resist or armor, you can always choose for the next item to be either Runic Bulwark or Frozen Heart.

ENDGAME
I already got to endgame in the previous section. Add a Guardian Angel, cause everybody will do it and it's awesome. Defensive stats + a second life.

Personal favorite build:
Boots of Swiftness
Spirit of the Ancient Golem
Rylai's Crystal Scepter
Sunfire Aegis
Abyssal Mask
Guardian Angel

My jungle route:
- Blue buff
- Wolves
- Wraiths
- Golems -> as you wait for Smite to get of cooldown
- Red buff
- Wraiths -> normally you have to wait here for about 4 to 5 seconds before they spawn. This gives you the time to check out mid. Can I gank early?
- Wolves

-> By now you should be level 4. From here on, the choice is yours: gank a lane or go to base and buy new items.

After the first cycle, I try to take out my own jungle in between ganks. This differs ALOT throughout the game and this takes practice. Maxing Tantrum first allows fast jungle clears and more time for ganks. Even in a 50 minute game, seconds count.

Try to prevent getting ********ed by the other team if they invade. Have your bot/top and midlane on the lookout to prevent ganks from happening to you! -> Getting ********ed anyway? Don't panic yet. You will have a rough start, but you can either try to get back at them by trying to take their blue (probably a bad idea though). Otherwise I take the following route: Golems, Red Buff, Wraiths, Wolves, Golems, Wraiths, Wolves. This should get you started too, you will probably not lose that many experience. However, not having your blue buff really denies you from early ganks.