Ambushing is the primary PvP mechanic in Pardus. It allows you to set your ship up to attack certain pilots if they happen to click on the tile on which your ambush was laid. It was introduced because players had found it difficult to engage in PvP, as people could simply run away faster than combat could be manually engaged by the attacker. With ambushing, you can leave your ambush and wait for it to trigger automatically, with no further input necessary from the attacker, thus making it very useful.
 Reasons to Set an Ambush
There are a number of reasons why people might decide to set ambushes. These might include Piracy, Bounty Hunting and Defending Territory. It is the simplest way to get PvP kill in pardus, and is the kind which you will encounter most frequently, whether you're attacking or defending. It's therefore a good idea to get acquainted with how it works.
 Choosing a Location
The first thing to think of with ambushing is where to do so. There are a lot of good locations spread around the universe, and where you lay your ambush depends on what you're trying to do. Pirates and bounty hunters might want to find a so-called "energy corridor" that is also a "choke point" which is where people are forced to fly through an area that is only a single-tile wide. Setting an ambush there means that you have a high probability of triggering, because everyone going in that direction will have to fly through that tile on which you're ambushing. For example, the choke at Lahola (13,2) is often used during wars involving the Empire, as it's a major passage from the neutral zone into the Pardus Empire Contingent. Generally, any high traffic area where you can hide yourself is a good place to lay an ambush. If you have a cloaker you can probably lay one in open space, catching people off guard who are only expecting ambushes on energy. If you can't cloak in open space and are willing to take the risk of the building owner demolishing their building, or being hacked - you can also try laying an ambush under a building.
Laying ambushes under buildings is particularly useful for defending territory, as it means you can protect your MO, or other buildings from attackers if you know that they're coming before they actually attack. If you catch someone in the act of attacking you, generally it is better to dogfight as ambushing is slower and more AP intensive.
 Selecting a Retreat Point
Most people set a "retreat point" before setting their ambush. With a retreat point you don't stay on the tile you set your ambush on after you trigger, but are instantly teleported to the retreat point - where you will automatically try and cloak a few times. You can set a retreat point before setting your ambush by going to a nice out of the way location, and selecting "Retreat Point Info" from the commands menu on the left of the Nav screen. Note that there is a limit to how far you can retreat from your ambush, and without an advanced skill you can only retreat to somewhere that is in the same sector as your ambush. Jumping through a wormhole will reset your retreat point otherwise. Setting a retreat point requires a piece of equipment called an "Ambush Teleporter". You have to set your retreat point before going on to the ambush screen, because after you tell the game to lay ambush, you wont be able to change it. Try not to be too obvious when selecting a retreat point, and try to make sure that you're at least out of sight from your ambush location, because if you fail to cloak, and the person you attacked survived - then they will be able to find and kill you easily. Lots of people retreat behind MO walls, as this makes ambushing offline reasonably safe. However, there is no guarantee that you wont be found and killed at your retreat point even behind an MO wall. Especially during war time.
 Setting Your Ambush
You can set an ambush on any location which allows PvP combat (not bases, planets and wormholes). On the left of the screen under "Commands" you will see an option labelled "Ambush (Retreat point info)". By clicking "Ambush" you will be taken to a screen which lets you set up and place your ambush. If you want to cloak, make sure you have enough AP to fail a few cloaking attempts and still be able to set an ambush, else you might end up being a sitting duck while you wait for more AP.
A quicklist is a short string of text that lets people quickly share and apply ambush settings. They are used by alliances or factions mainly, to ensure that their members are all ambushing for the same people. To apply one, just paste it into the quicklist box at the bottom of the ambush screen, and it will automatically fill out all the settings, so all you have to do is click "lay ambush".
Several people can ambush on the same tile. This is great for making sure you actually manage to kill someone, as lots of people can easily survive one person ambushing alone, but not two or more. Ambushers can stack join an existing stack whenever they want to (but it's probably best not to join random stacks of people). When someone who is being ambushed for runs into a stack, the people who are ambushing will trigger and attack one after another. If the person dies, then credit for the kill goes to the person who landed the killing shot, not the whole stack. If there are more people on the stack than are needed to kill the person who tripped it, then those people will remain in ambush until someone else runs along and triggers them, or they get bored and leave.