When starting to play with malphite you have to understand first of all that he can be 2 kinds of rolls tank or off-tank so you have to choose what you want to play as. Then you have to choose if your a good jungler or that your a good aggressive top player. Malphite has 2 AOE attack's his E and his Ultimate so you have to be aware of those to be ready once you rush into the battle. Malphites Q is one of the most annoying harass ever! you can use it and with its speed bonus you can just RUN up to him and own his ***.
If you going to gank make sure your Ultimate is up so you can get the kill/s with no problem with the help of the lane mate who your ganking with.
Basically I recommend Malphite just you have to get to know him, and his tactics/moves.
So get out there and may the enemies always loose GL.