This is my first guide and I don't imagine it will be the best, but I feel it's at least worth it to share a bit of what I know regarding Malphite. Why Malph? He is my most favorite champ to play as and I usually play him as a top tank. People may think that's boring, but I say it's only boring if you don't play him as the playstyle he was intended for. My belief is that he works effectively as a tank, and if you think so too, you might like this guide.

Pros:

Heavy Tank - This big guy is not just a tank. He's the definition of "Tank". He's able to take on a lot of abuse granted the opposing champ is an AD Heavy champ. The fact that he has a pocket shield enhances his survivability by a lot compared to most champs.
Easy Escape - If you're in a tight spot, Malphite has the abilities necessary to make a quick escape. Q not only slows a champ, but also has him steal movement speed from the targeted champ and R gives him nice range to make a quick escape. If you need another ability, there's always Flash.
Team Fighter - For similar reasons as Easy Escape, Malphite is a powerful team fighter. Q and R can be used to keep enemy champs from escaping, giving your team the window they need to get some easy kills.

Cons:

Magic Squishy - While he can take a beating from an AD-Heavy team, Magic is another story. Since armor =/= MR, you'll need to build the proper items to protect yourself or face getting blown up every single time by magic users.
Kinda Weak - I mean this in the offensive way. Malphite deals physical basic damage, and his moves are usually at their strongest when in a team fight as opposed to 1v1. In 1v1 it's more about outsustaining and if the opposing champ has a powerful move and uses it, it could make the difference on whether you survive or die.
Kinda Mana-Hungry - For most of my games, I've run into the issue where I have no mana to follow up on a gank by my jungle or to just get that extra push against an enemy champ. This is one of the reasons why I included the Corrupting Potion in the item set: for a bit of extra mana access.

Farming is a must for Malphite. To get some of the items on this list will require a pretty hefty sum depending on how fast you want to build. In general, if it's an AD-Heavy champ for your opponent, there's really no need to worry. Just try to last-hit as many minions as possible, using your E on occasion or when the opposing champ is close and wants to attack you. Against AP-Heavy champs, it's better to farm under turret so as to avoid any abuse they can inflict on you. Granted this doesn't stop them from throwing a ranged attack on occasion, but it prevents them from closing in with a move that requires them to be close. Kite as necessary against ranged attacks and keep on farming. Another general rule is to back off when your shield is down and let it recharge. Your shield can give you a little more padding to farm if the enemy champ aggros you and while it's slow at the beginning, it'll speed up later in game.

Some guides aren't meant to be followed strictly, but to act as an idea on how to properly play a champ. That being said, I hope my guide on Malphite can help those who like to use him, but need some words of advice from other players. I might follow up with some other champs if I find myself building them a particular way that might be nice to share with the general public and I may come back to this guide and expand on it even more. See you on the battlefield.