A tank Maokai will have a bad mana starvation problem, but with your clarity you should be fine.

Early game try to lane with another ranged champion, as long as you can out-range the enemies.

This build is not made for kills. It is made for assists. So do not be disappointed when you have low kills. You will have high assists, which is the goal of any tank.

At the end of this build, you can add a bloodthirster or another high AD item to become a pusher, if it is necessary.

The Thornmail/ force of nature are interchangeable depending on the enemies you are laning against. Obviously if you are against high AP champions you don't want to worry about the thronmail until later. Your first ruby crystal will go to your warmog. If you are careful you should have no deaths until you have enough for your merc treads and hopefully longer.

You are an initiator, but are not invincible until the end of your build. Ult only when the other team has committed to the fight, and won't turn around and run. Your Ghost, Snare, and Slow will ensure you get assists and can help kill the other champion.

If you level in time, level 4 saplings will kill any group of minions. If it doesn't, and E-Q combo will. Creeping at 18 is fast. Make sure to creep as much as possible to fill your warmog.

As far as jungling goes, you should always be the one to initiate the baron with your ult. 20% less damage will speed the process and ensure nobody is too low on health once he is killed.

Your ult is touchy. It is useless if used at the wrong time, but it can also be a game changer. It is great for preserving the life of teammates, but also yourself. Since you will have a slow movement speed, there will be times when you have to turn around and fight, knowing you will die anyway. Ult.

It is also incredibly good for kill stealing.... Just like smiting to steal a jungler's buff. Mean... yes. But useful.