Single diodes can take up a lot of space, so if your layout space is limited I suggest taking a look at ESD Protection diodes - they come in a variety of packages, ranging from 1 pin protection and up.
Don't forget a high impedance input current limiting resistor, so your ESD protection doesn't blow up when connected to 12/24V.
If truly high power, use a dedicated tranzorber diode - they handle power well, and also protect against lightning surges.
http://www.onsemi.com/PowerSolutions/parametrics.do?id=248The HDMI versions has up to 19 pins in a single package and are unidirectional and handle high-speed easily.
The USB versions has 4 pins, also unidirectional and low channel input capacitance, and may be easier to place close to the inputs.
The added bonus of using an external ESD protection diode solution, is extra ESD protection