Rules of Thumb
Tell people what your name is, or what you would like to be called. Before you tell your name, others will know only your gender and approximate age ("in your twenties"). Telling them your name (and learning their names) will make it much easier to interact. In some places, people can even be hostile to those who don't introduce themselves shortly after spawning or arriving in a new location.
Read The Laws!
The best rule of thumb for anywhere you spawn is to make sure you read the laws! If they aren't available (they are usually in note form on the ground) then don't be afraid to ask around.
Reading the laws you can do by clicking on 'objects', which lists all objects on the ground on that location, including notes, and then on the eye-buttons to read the specific notes that you see. Most locations with at least a few people living there will have a note with general rules or laws, but not all locations have laws.
In most (but not all) places, it is not a good idea to knock on buildings, go into buildings, take items off the ground, or hit people.
There are no game rules stating you must follow the laws of your society, but remember, if you choose to be someone who breaks the law, be sure you can get away with it unless you want to face the consequences.
Keep It Original!
Another good idea is to make your characters as original as possible. Using outside names of people and organizations is generally frowned upon by serious roleplayers. It shows a lack of imagination, and imagination is what makes Cantr so great. Even if your character does not assume the aspects of the real life person, your character will be taken much less seriously than a character with an original name.
Out Of Character \ In Character
OOC is the tag most use in game to indicate that the "player" uses to convey a message from their point of view rather than the characters. This is generally frowned upon in the game but is still used in certain cases. If you *must* speak OOC, it's preferred you do so in a whisper.
North is Right!
In case you're unaware, the map you see on the location page is tilted 90 degrees clockwise, placing north on the right-hand side of the map, where east would usually be. So, north is right, east is down, south is left, and west is up. Please remember this when mapping a region, or navigating the seas! Without this knowledge, you could easily become lost!