Guild banners and allies

You do not need a charter or to go to a special area, though you can create a guild by speaking to a Guild Registrar in a city.

You will need to have 1 silver in order to create a guild. Then all you need to do is open the Guild window (G by default), choose a name (31 character limit) and guild tag (an abbreviation that will show up next to your character name, up to 4 characters), and that's it.

Note that guild members don't even have to have be on the same Home World (server) as you, though you do need to be on the same Home World if you wish to play World vs. World together.

The default maximize size for a guild is 50 members. In order to increase this size, you will need to speak to a Guild Registrar. The following table from the official wiki lists the costs and upgrades as follows:

Tier   Membership Cap    Cost
 1          50         1 Silver 
 2          100        1 Silver
 3          200       10 Silver
 4          300        1 Gold
 5          400        1 Gold
 6          500        2 Gold

Left-clicking on the ground is the most reliable way to deselect all targets.

ESC deselects any selected targets, but if nothing is selected you will bring up your menu (can be annoying mid-combat).

There is also a key binding to target the nearest ally, which will select yourself if no other allies are around. This is useful if you are having trouble finding a patch of ground to click on. This key is not assigned by default, so look for "Nearest Ally" under Targeting in Options->Controls.

You can also select the next closest target using TAB, in case you do actually want to direct your spells towards a different enemy then the one you current have selected. Then again, a left-click on the target works more reliably if multiple targets are in view.

There is also a Guild Wars 2 printable keyboard layout to help you visualize the default key bindings.