Walk straight to their raptors if it's in their top side, ward them, go back and buy sweeper.

Start W. Sometimes you might start Q if your team invades or you get invaded, so you can slow them.

You will be starting your raptors without leash. This confuses enemy since they don't know where you start and gives your lanes the bonus of not leashing and getting earlier to lane.

After raptors get a point on your E.

Next take Red buff. You will be keeping your W up despite it costing HP for faster clear. Then head to your Krugs. Smite the big one as late as possible when you're very low since Mundo does more damage when he's low.

After taking the Krugs you should back ASAP. You have around 400g and time should be around 2.30-2.40 after clearing you red side. Buy Hunter's Machete and head to your blue buff.

You get to take your blue buff just in time to get to scuttle crab when it spawns. Remember to use your cleaver to start the fight, since it does damage based on enemies current HP. You have 2 refillable potions, almost full HP and 2 jungle items so you can contest Scuttle 100% and you will win almost every time unless you do something very wrong.

You should not use your W on single target camps, since you will be much healthier without using it. If you know you're going back soon, it's OK to use it.

After scuttle head to your Gromp, smite it unless you used your smite on scuttle crab while contesting it. Then take wolves and you have done your full clear. Now you can look for a gank or just go back. Getting both scuttles should be easy and if it can be done you should do it. You should get most of the time at least one of them.

You should go back around level 5-6. Get your red smite. For some cases if the enemy has something like Ezreal/Nidalee it might be good to take blue smite, but red smite should be the standard. If you have 900g you can just go for the Bami's cinder.

Buy control wards as much as you can since having vision control helps your teammates avoid ganks and helps you to track enemy jungle, deny them vision and give you better ganks.

When you're level 5-6 and have gone back you can solo dragon very easily and you should be trying to get it, since every drake expect infernal (which is very good) is godlike on Mundo. Prioritize dragons over heralds, but getting heralds pre 14:00 is very good and gives you and some of your laners good chunk of gold and maybe even first turret. Herald takes 2.5 plates so you should try to get tower to that and just first turret it with herald. If you get to kill enemy toplaner or/and their jungler and you're around the herald side you should take it 100%. Having vision if their jungler/toplaner is alive is a must. You should solo it, so the enemies don't suspect anything and if your top and mid keeps pushing, enemies can't leave unless they want to lose platings and/or minions.

After you have your cinderhulk you can just powerfarm yours and enemy's jungle.

You should avoid ganking pre-6 since you need to hit cleaver to make it work and most of the times farming is just more worth it for you. However if you see a sure gank close to you where you might get summoners or kills it's obvious you should take it.

Going for counterganks even pre-6 if you're close is important, since Mundo is very strong duelist.

When you go for a gank it's good to see if the area you're going through is warded. It saves you time, so you don't sit in bush not knowing do they know you're there.

When you go in you should pop your ulti for the movement speed and to be able to tank enemies, like their botlane and maybe even some turret shots if they get that far. Keep you W on for the tenacity If you have ghost it saves you your ulti and ghost+ulti makes you insanely fast - a monster who can't be escaped. If you have red buff you don't really even need to hit your cleaver since you can just walk to them and slow them.