Link to original: http://sphynxcatvp.nocturna.org/articles/sc-shieldingoverview.html
Shields are your primary method of protection from psychic/psionic attack and possible damage, with a variety of different styles used for different purposes. While some people may settle on a preferred shielding method and stick pretty much to that, it is recommended that you learn and practice multiple shielding methods so that you're better prepared in different situations.
This overview is not a complete list, since anyone can develop new methods. As with any situation, you should become proficient at analyzing a situation and determining the best shielding type to use. As with all Workings, intent is the key - you have to be 100% sure of the intent you give to the shields. Shields can also be given different colors or shapes depending on your preferred operating style.
Note: To anyone with enough advanced knowledge, any or all of these methods may be broken, detected, or worked around. An opponent may or may not have enough knowledge to work past multiple methods. And, last but not least, don't go developing a "I'm using uber-shields and you can't attack me!" attitude, because someone, somewhere, will most likely take potshots at you to test them either out of boredom or because they find that attitude annoying.
Energy and focus/concentration requirements for any of these may vary depending on your skill and practice.
Uses incoming energy to power the shield. If needed, you can filter out the energy you don't want out of an incoming attack and just use the parts you do want. An example of that is to filter out emotions and just use the attack's base strength. Or you can use all the incoming energy and convert any unwanted types to a wanted type. This is generally a low-powered variety good for everyday use.
An absorption shield that also attacks the user. Retaliation can simply be using the energy to generate your own attack using the same or a different method, or the retaliation can be latching onto your attacker and draining their energy - particularly useful for psivamps.
Uses the incoming energy to heal any damage you've already taken. You have to understand how to do this
Absorbs, but preferentially seeks specific energy types. This can be used as a method of setting up a link to someone else, and aids in detection.
Constantly altering the appearance of your shield. This technique can be applied to many types, provided you can maintain it. The Borg in the Star Trek TV show use ship shields that constantly change in frequency in order to defeat things like tracking beams - this is a similar idea.
By pulling in bits of energy from people around you, you can alter your outside energy "appearance" to look less like yourself and more like, say, the mundane person standing behind you in line. This is often used as a cloaking method. An example would be pulling fresh-dropped branches over your hiding place in the woods.
Generates random amounts of "psi noise" in an attempt to confuse any scan or attack attempts. Mix with a redirection method for better results. An example would be turning on several radios at once, each tuned to different stations.
This method redirects incoming energy and sends it back out. While it sounds similar to a mirror shield, it's different because you need to interact with the incoming energy in order to redirect it.
As above, but in the process of interacting with the incoming energy, you can alter it's "fingerprint" to hide it's initial source or characteristics. For example, you can change an attack blast's "fingerprint" so that it no longer reads as an attack and fire it back at a person who's shields are designed to block their own attack energy.
This is a mental mirror surrounding you that causes all incoming energy to be reflected back out without effect. Can also be thought of a a "rubber ball" shield. If you like, this can also be modified to form a filter, only letting in the energy you want. Two or more people with mirror shields may end up with a "volleyball" effect, bounding energy back and forth between them, until one person's concentration slips, or one of them does something else with the energy being tossed around. An example would be a completely shiny surface, similar to hematite.
As above, but instead of reflecting energy back the way it came, reflects energy in any random direction, or ricochets off at particular angles. An example would be multifaceted crystal that throws light everywhere.
This can be visualized as a ball, egg or some other shaped mass of energy surrounding you. You can give it particular colors if you desire, or leave it colorless. This form of shield blocks incoming attacks without reflecting them back to the attacker. It it very versatile, and good for a beginner to start with. Because it's so basic, though, it can be easy to break by more experienced people.
Often visualized as a ring or ball of fire (or blinding white light) that destroys incoming energies similar to how meteorites are destroyed coming into earth's atmosphere. It requires either "set it and forget it" programming, or awareness of incoming attacks to be able to neutralize them. It IS more energy intensive, and not recommended for long-term defense.
One or more layers of shields that also rotate on an axis. Commonly used with basic walls, but can be modified to use most shields. The spinning makes it difficult to attack the same spot multiple times, and can also make scans difficult.
Interlocking two or more types of shields to make a more robust defense system. You MUST be skilled with the shields you intend to use in a layered format. This will take practice if you're not used to it, and some common sense is required - for example, don't put retaliatory/attacking shields under a simple reflective shield, for example.
Nearly any shield can be modified to filter, but often the filter capability adds a weak point in the shield where the preferred type of energy can be let in, so this is something to keep in mind in combat situations. A non-combat example are empathic filters that tone down the noise level of people's emotions.
More potent (and thus takes more concentration/energy) than simple camouflage, This is much closer to "I'm not here" compared to camouflage's "I'm not the person you're looking for."
Typically these are basic wall types, however they can be any type depending on the person making them. These operate on a larger scale, covering the space you live in (house, apartment, etc.) Residence shields are commonly used to dissuade wandering entities from entering, much like an alarm system discourages burglars from breaking in to steal your stuff. (While these are commonly called "house shields" I use "residence" in an effort to show that you do not have to have a house in order to use them.)