Suicide ganking is the act of killing a player's ship in a situation where it is sure or very likely that your ship will die in the process. Suicide ganking is typically done in high security space where you will be destroyed by CONCORD (space police) or faction ships/gate guns (other space police). In low security space, suicide ganking can be done against a target on a gate or a station (provided that you cannot tank the sentry guns), or against a target that is heavily guarded. In zero security space, a heavily guarded target is the only one that can be considered a suicide gank.
There are four common objectives of suicide ganking:
If you can identify and destroy a target carrying valuable cargo, it is possible to profit from suicide ganking. To profit, two things must happen; the item(s) in question must be dropped from the ship when it explodes (known as loot), and the profit you make from the drop must be worth more than the ship(s) you lost to acquire the loot.
Griefing is the act of intentionally making another player angry by doing something to them. Griefing can come in many different forms, but one of the most common forms is suicide ganking. For nothing else, some players may suicide gank others simply to make the victim unhappy. The target of a griefing suicide ganker can be either the things inside of the ship's cargo hold, or the ship itself. Some ships are incredibly expensive, making them very juicy targets for suicide ganking. There are also lots of types of modules, blueprints, and other items that are very costly to lose, making them as interesting as some ships.
In this case, grief and profit are not the primary objective of suicide ganking (although profit can happen, and grief most likely will). Suicide ganking enemy logistical ships is a great way to limit their ability to attack, defend, and grow. Taking out a ship that is either very expensive and logistically valuable (i.e. a jump freighter or carrier) or is carrying valuable resources for the enemy can cause a lot of damage.
With suicide ganking, your first goal is to find something expensive. The more expensive the better. Alternatively, you could go for tears - in this case, most targets you can kill are good options. If you don't get any tears right away, fear not! You can always convo or mail the victim to mock them or try to piss them off.
Regardless of your objective, blowing up expensive things will likely get you to it.
In order to figure out what items are in the cargo hold of a ship, you need a Cargo Hold Scanner. It does exactly what the name implies; it scans the cargo hold of whatever you activate it on, and reports back with what's in it. If you're scanning ships, it's also advisable to fit a Passive Targeting module. This prevents the ship you've targeted from knowing that you've targeted it before you perform an act of aggression on it (Note: scanning a ship is not an act of aggression). If your target is active and in an expensive ship or carrying expensive cargo, they will probably turn tail and run if they see someone targeting them.
Generally speaking, when suicide ganking it is better to have several cheaply fit ships as opposed to one expensive ship. As well, it is advisable to engage with more DPS (damage per second) than you think you will need. The whole point of a suicide gank is to destroy the target as quickly as possible to avoid the space police blowing you up before you blow the target up.
There are two main kinds of attacks: DPSing and Alpha'ing. DPSing is any kind of attack that takes more than one volley of your weapons to kill the target. Alpha'ing is an attack where you only fire one volley of your weapons before the target explodes.
For suicide ganking you will need however many people it takes to kill the target. For suicide ganking for profit you will need however many people it takes to kill the target, plus one ship that will scoop the loot from the wreck.
This is the easy part, but if there are multiple damage ships involved, it can take some coordination. If you are the only DPS ship, lock the target and fire as soon as you have a lock. You should prime your weapons and scrambler/disruptor so that they fire as soon as the lock is made.
If there are multiple DPS ships, there are two approaches:
Once you're in your pod, warp off to a safe spot (having one ahead of time is especially important in low/nullsec). Make sure you wait out your aggression timer (visible in the top-left hand corner of your screen) before attempting to dock.
If you are a looter, you should scoop the loot and dock in a station/get to a friendly POS as soon as possible. It would be unfortunate to be suicide ganked with all of the loot from a suicide gank in your cargo hold.
If you aggressed the target in any way, check your security status to make sure it hasn't dropped low enough for you to become an outlaw. If you can take another security status hit, feel free to repeat as desired.