All glyphs need to be signed with a rune particular to a registered member of the Grey Order. Grey Mages who are not members of the Order are assumed to have learned the rune of a genuine member: either by torturing him until he gave it away, buying the information from him, or spying on one of his glyphs. The rune-signatures fade away as soon as they are drawn, so you can't steal somebody's signature just by looking at a glyph they drew. If you catch someone in the act of drawing a glyph that's another matter, but members of the Grey Order tend naturally to check nobody's watching before they sign their glyphs.
Glyphs can be drawn in any substance, and using any material. However, accuracy counts: so while you could use your finger to draw The Eye in the dust on someone's floor, it would a) only last until they swept up and b) be unlikely to be accurate enough to provide a useful picture.
Glyphs are classified as Simple, Demanding or Taxing; this is an OOC classification and serves to distinguish whether you can use them in session or not. Simple glyphs can definitely be drawn in session and could potentially be drawn without anyone noticing. Demanding glyphs could be drawn in session, but you would have to visibly do so for a length of time. They couldn't be done covertly. Taxing glyphs could absolutely not be drawn in session, though you could bring a piece of paper with a Taxing glyph already drawn on it.
Location/Tracking (Simple)
Location and Tracking are two separate glyphs, but the Grey Order classify them as one. When you draw the Location glyph and drop a stone onto it, the stone will bounce in the direction of the nearest Tracking glyph.
Poison Ward (Simple)
Draw this glyph in the centre of the floor and place a piece of food or drink in the centre just before you sign it. If it had been poisoned before, it will not be any more.
The Closed Eye (Demanding)
The Closed Eye glyph makes the item it was drawn on appear to be uninteresting. People don't notice it - it fades into the background. It only lasts for about ten minutes, after which the Citadel cuts the power. It takes about half an hour's concentrated effort to draw.
Agony (Demanding)
Tattoos are painful enough anyway. If they're in the shape of the Agony glyph, they cripple the limb they're drawn on; the person who it's drawn on cannot use it at all. The effect lasts for as long as the glyph remains on the victim's body. Drawing this glyph on somebody's head won't kill them - it'll just make them into a vegetable until the glyph is removed, at which point they're back to normal. A tattoo glyph could be removed by shaving off a layer of flesh, or an ink glyph could just be rubbed off, given time.
Beauty (Demanding)
The glyph created by this is strangely attractive. Far, far more attractive than any mere arrangement of lines should be. Anybody looking at it who doesn't have a very good reason to move on (someone's trying to kill them, the building is on fire, etc.) will stand there and gaze dumbly at it for anything between thirty seconds and half an hour, depending on their strength of will and how aware they are of what's going on. It won't trap people for ever, but it serves as a very good diversion.
Sabotage (Demanding)
Whatever this glyph has been drawn on will become shoddy, unworkable and cheap. A strong fence will get woodworm and decay. Food will go sour, a statue will become shoddy and start to corrode, and mechanical wings will start throwing gears.
Returning (Taxing/Simple)
Spend several hours drawing the first Returning glyph somewhere you think will be safe. Then walk into danger unafraid. When things get nasty, quickly draw the second Returning glyph (which counts as a Simple glyph) on something you are carrying. (Paper will do nicely.) You, and anything you are carrying, will teleport back to the first Returning glyph. After this, both the glyphs are useless, so it's probably a good idea to erase them.
The Open Eye (Taxing)
Once drawn, the Grey Order can use devices in the Citadel of Steam to look through this glyph until it is erased. It takes several hours' effort to draw.
Protection (Taxing)
This creates a glyph about a metre wide, which only the person who signed it can enter. It remains in effect for a week; after that, you will need to re-draw it.