This is my first build that I've published, it has decent early game harass due to sapling and end game it can be very difficult to kill due to its health regen, Maokai's passive and the amount of armor/magic resist it has. This is a basic strategy for tanking as Maokai.

This skill sequence allows for good early game damage with sapling and what i see as a better sustained damage for later with leveling Twisted Advance and Arcane Smash up side by side, also, while they wont stay rooted for as long as builds that rush Twisted Advance they do get slowed more with Smash which can allow for some additional beat time for your team, It also allows for a higher area damage output in team fights.

Mark of Insight - While i don't build Maokai to be damage, the Magic Pen comes in handy so you can be a little more help end game, and to help your harass early game

Seal of Resilience - I take solid armor for the early game aid, while you may have a decent harass, and your passive for some survival, if you get caught to far from your turret your easy prey for enemies, these seals give you some extra survivability early game, allowing you to stay in lane longer, and take more of a beating.

Glyph of Shielding - While i may take solid armor seals, i find for mr its better to take per level glyphs, early game most spells aren't as effective and you can take more of a hit then late game, so taking the per level glyphs allow better overall survivability for a match

Quintessence of Fortitude - Solid health quints again add for some decent early game survival, it allows you again to take more of a hit like the seals, and makes your passive heal you for slightly more, again, allowing you to stay in lane more.

Unlike some other tanks, Maokai lacks a stun, what he lacks in stun he makes up for in slows and roots, i like to take Exhaust as it flows with his other abilities so well, allowing for an extended slow if you Arcane Smash, Exhaust once its about to end, and Arcane Smash again. Flash i see as a must have, it allows you to get in and out of combat in a pinch.

Twisted Advance is in my opinion one of the best combat initiating moves in the game, if someone gets too far forward its easy for you to get in, root them, and allow your team to come in to pick up an easy kill, it also works well to get to the middle of your enemies to drop Vengeful Maelstrom which tends to make the enemies scatter, again, allowing your team to pick up some easy kills, or they'll have to fight in it, dealing reduced damage to your team, while allowing you to pick up some bonus damage when it goes off. Directly after dropping your ult you should toss a sapling at your focused target, in most combats people will be to concerned with player placement to notice it on the field to get away. It is important to have awareness yourself though, if the enemies do begin to scatter or fall back out of your ult, it never hurts to get rid of it, its on a short cooldown, so you can get rid of it and wait a moment to place it again, and its just going to be wasting your mana if no allies or enemies are in it, alternatively, it may help to leave it down, if your doing well on mana and your team begins to push them back, having it still down will allow your team to fall back if things go south, the enemy will tend to not want to run through it because of the damage it can deal, or underestimate it and allow you to pop it to pick up a kill.

Early game I prefer bot to solo top, typically with the skill build i take if your laning with someone you can root them and exhaust allowing for early game kills, with the rune build I use, you have decent enough survivability to allow your partner to pick up a kill and get back before taking to much damage yourself, if your soloing i prefer to take a more defensive route. Sticking close to your turret and trying to force your opponent to over extend allowing you to either root them in range of your turret, or for your jungle to gank.

Late game however, things change, like always its important for a team to stick together, but end-game your so tanky its ok to be aggressive, still stick near your team, but make sure to keep pushing, if your close to a turret with your team but no minions push anyway. Even if you only have 1-2 other people its ok to push a turret with a defender, make sure not to let yourself get overrun though, this works everytime, push the turret making sure the turret is on you, but drop your ult centering it on the turret, even if you don't think an enemy is near. With that if an enemy runs up they will target you thinking they can pick up an easy kill with the turret on you. However you'll have so much armor and health regen you can more than tank a person and the turret for a few seconds while your teammates take out the turret. IF things aren't looking good, fall out once you get to about half health, you've got plenty of speed to fall back and lots of hp/5 to allow for a quick recover.