Maokai is a pretty easy and effective jungler, he can easy kill the creep in the jungle and he can make some good ganks with he's Twisted Advance. When you go into team fights with maokai, remember allways to pop your ulti Vengeful Maelstorm. It will help your team alot with the damage reduction. and with the movement speed from Shurelya's Reviere and the slow from Randuin's Omen you will suport your team alot in teamfights. He is very effective in teamfights with he's ulti and cc, and it's hard to flee from a feeded maokai.

You start at wolves, and throw a Saplling Toss about 1:10. Then you throw 1 more, and then you throw The last on the Wolves when they spawns at 1:40. They should be dead before Blue spawns at 1:55. Then ofc you go to blue (best with a pull.) Then you go witches and then Red buff, and then golems. When you got about 720-750g. you recall and buy Philosopher's Stone and Boots of Speed. And then you can go for gang if it's possible, or just go farm more. Philosopher's Stone is also a good combo with Maokai's passive Sap Magic ( Each time anyone uses an ability near maokai he get's a stack of Sap Magic. It stacks up 5 times, and when you have 5 stacks your next attack he will heal himself for 7% of he's max HP.

Ofc you shall take the smite for jungling and creep farm.
Flash is a good choice because of the help at gangs. And it may help you at fleeing and towerdiving. Another good choice is Ghost. It can also help you at the gangs and to follow your enemy to the end of a fight.

When you play maokai, a good idea is to throw a Sappling toss in front of a fleeing target and then use Twisted Advance on them. Then cant your enemy flee from the exploding sappling toss.
Then when you have used your Twisted Advance you move in front of the target, and smash them back to your team with your Arcane Smash. If you maybe go from wolves to Witches, you can just throw your Sapling Toss and then when you can see the witches you can use Twisted advance to get through the wall.

For marks i would take Greater Mark of Focus: Because of maokais needs he's spells in any fight, it would be great if he could use it more often.
For Seals i would take Greater Seal of Resilience: Because of the armor maokai will more easily farm the creeps in the jungle, and it will help him vs ad carrys.
For Glyphs i would take Greater Glyph of Shielding: The magic resist per lvl will help you vs ap carrys. So with the armor from Greater Mark of Focus and the magic resist from Greater Glyph of Shielding, maokais tanking should be better.
For Quintessence i would take Greater Quintessence of Fortitude: The HP is good, because it's not fun to gang in low lvls with no health..

It's good to start with a Regrowth Pendant and a heal potion. Then you should go for Mercury's Treads for tenacity, And then fast go for a Shurelya's Reviere for the movement speed at ganks and a Randuin's Omen for slow at gangs and teamfights. Frozen Heart is good vs ad carrys because of it's slow debuff, and the mana and cooldown reduction will help you with your abilities, and you can stay longer before you go oom. Aegis of The Legion is a little support with the damage buff, and it gives you all the tanky stats. Frozen Mallet is good with the slow and the HP it gives you. It's also a good choice if you are vs much AP dmg. To chance your Aegis of the Legion with Banshee's Veil for the spell block and more magic resistance.

In this build, the masteries is 0/21/9. In Defense i go for the most tanky masteries and the Though Skin and Bladed Armor is for Better jungling. In Utility i go for the mana and mana regen, and Runic affinity is for the longer duration of the buffs.

When you farm lanes with maokai you ofc. you need to last hit creeps. When there is many creeps in a group, a good idea is to throw your Sapling Toss at them and then use Arcane Smash. Another good idea is to throw a Sapling Toss into the brushes as a ward if the enemy jungler comes. If you play solo top, it's also a good idea to let the enemy use some spells near you to pop your passive, or use your spells to pop it if you are on low life.

If you use this guide you will get high HP. and you will assist your team ALOT in teamfights with the items you got. You can easy tank a teamfight and you can survive in long time with your ulti and items. It's a good jungle guide and you can make some nice ganks. Maokai will fast kill all tht jungle creeps, and when he need to hold lanes he's passive also help him alot.

Don't let your team go into a fight before you, because if you are the only tank, they will probably die. So don't be afraid of going into a fight! (Ofc don't just run into a bad fight and think that you can handle it, because it can be a problem sometimes. Don't gang a lane if the enemy team is very strong there already in low lvl before you have your Twisted Advance and Arcane Smash, cut if you don't have these abilities you will probably not get them. ( But if they are pushing alot and you can come just behind them and make sure to get the kill, it's ofc a good idea.