Dr.Mundo is one of the best tanks in world of League Of Legends.I have scored 850 wins in rank game and 1500 in normal game with Mundo.My scores has a lot of kills and assists but a almost none death in each game.Mundo is a good hero because he is a tank with a damage and he get very easy kills.His only disadvandage is that all of his abilities need help to cast them.

You can change your summoner masteries it depends on your summoner spells

Ignite is a good spell for Mundo
Flash is also a good spell for him

R>Q>E>W
Use you.
Then throw your .
After that open And then open

I've seen people do it and I don't think it's a good idea at all;
1. He has bad jungle sustainability (no health return)
2. He is a slow jungler
3. He has weak ganks (Cleaver can be creep blocked)

However, that doesn't meanis a bad idea! Mundo is a great smite carrier along with your jungler. The reason you might want to double smite is because;
1. Mundo is beefy enough not to need a second spell
2. It becomes near impossible to have dragon and baron stolen from your team
3. If your jungler gets picked you can still fight the enemy at baron/dragon and possibly get a smite-steal.

I wouldn't recommend running double smite in solo Q however. As it requires more team cooperation.

This is possibly the most important stage of the game for Mundo, if you can't win your lane (Out-harassed, out-CS'd, Ignited, etc.) then you're going to be in a bad spot for the next 20 minutes.
Aggression is the key, you need to control how much you harass and commit. For example; if you try to fight them when they have a large minion wave you're obviously not going to win (minion damage+can't hit cleavers through minions). The best time to fight them is after you have landed some well-placed cleavers or during a jungle gank.

I highly discourage using Masochism or Infected Cleaver to last hit too much, eventually you'll notice the effects this has on your health pool. The best time to be using these two skills for last hitting is when/if you are pushed to your tower and you don't want to miss any gold.

To last hit at towers;

Let the tower hit the Melee creeps twice then last hit them.
Hit the Ranged creeps once (WITHOUT Masochism on), let the tower hit them, last hit them.
Cannon creeps are a bit trickier but you can throw a Cleaver then Masochism effectively doing a "double strike".

(These amounts change depending on the units health at the time of the tower hitting them, use your gut instinct!)

I prefer to spend most of Mid game farming/pushing but it's also optional for Mundo's to roam a little.
When roaming you want to keep these things in mind(listed in order of preference);
1. Is dragon/baron warded?
2. Are any lanes gankable (ie. pushed to the tower)
3. Are there any MIA's you can call (dem lazy teammates!)
4. Do we have sight of the enemy jungler or his buffs?

So most of roaming comes down to wards and ganks.

(Mundo isn't a strong roamer, doesn't have hard CC but he does have good mobility over the map. Preferably you'd want a roamer like Alistair, Eve, Maokai, etc.)

Most of the time late-game is decided by Baron but it can also be decided by pushing harder then the enemy team, if you have good ward coverage in their jungle feel free to push a lane until you see them coming. If more then 2 people come to gank you it leaves your team free to push the opposing lane/do another dragon/POSSIBLY do baron if you're pushing bot lane.

And when it comes down to team fights remember that you are NOT a tank, don't be all macho. Just chill until your tank initiates then start roflstomping enemy carries.

The biggest difference between Normal games and Ranked games for Mundo is that the enemy sees you picking the Doctor. They then proceed to grab 2+ ignites and often you'll see one. So the best way to keep Mundo going on his merry way is to grab Quicksilver Sash! You'll want to buy it straight after your boots of choice.