If this is your first time developing quests for Avalon, we recommend you start with something small so we can get an idea of your style and skill and so you are not overwhelmed.
Begin with the concept of the quest firmly in your mind. What are the requirements, what existing and new locations and objects are involved, how does it work from start to finish? How does it end and what are the failures possible along the way? A good quest will rely on more than GIVE X TO Y and draw in a number of facets of Avalon, rewarding puzzle-solving over brute-force and automation. It may also have random outcomes influenced by the player.
What are the rewards or effects of the quest? Consider also repeatability. Most quests in Avalon reset over time. Others (such as the Long Night and the wisdom/evil totems) are stateful and require another player's actions to reverse them. But in all events the quest must not be repeatable immediately for infinite gain.
Once you have this settled, you will need to submit it to one of the Omnipotents for approval. A descriptive paragraph or two will suffice, depending on magnitude of quest. This will enable us to determine whether and where the quest can fit into Avalon's ongoing story. You should avoid going any further without confirmation from us to avoid wasting your time - a quest may be rejected for various reasons, many not even related to your skills or writing.
So you have the go-ahead and need to begin writing the quest. You won't be coding it into Avalon, so you can concentrate on purely descriptive writing, but you should bear in mind all the possibilities raised by the quest so you can write for every eventuality.
A good start is to make a list of all the objects involved in the quest. Take the captain's safe for example. We'll need a pouch of obsidian spheres, a locked safe, an open safe, and an emerald. For each of these, you'll need brief, examine and inventory descriptions. If you have permission to add a new CCC to Avalon, there are additional requirements. See HELP FORMAT for more information on this.
New locations may form a part of the quest. HELP FORMAT gives the requirements for these, and you should also include a description of how they are linked together and how they are linked into the existing land.
Next comes the hard part. You need to consider all the actions and responses related to the quest, and write messages for each one. Consider both successes (when they are doing the right thing) and failures (when they're doing the right thing at the wrong time, or when they're doing the wrong thing altogether, for example). A good quest is non-linear (does not rely on everything being strictly in order), open-ended (can reward the questor for additional actions or going beyond the call; this may require additional coding) and provides subtle clues for the adventurer who is on the right track.
Consider syntax. A questor should not be foiled because he is using "LIFT SAFE" instead of "TILT SAFE". A number of verbs in Avalon are already synonyms, and objects can be given multiple names (cube, safe, metal cube), but consider other, more natural syntaxis like "POST LETTER" versus "PUT LETTER IN MAILBOX". Specify in your comments all the different names for objects and all the variants of syntax you can imagine.
For every action, therefore, you need to write the game's response. You also need to write text for things that happen without the player's direct action, or that happen gradually after a player's action. These little touches will improve the atmosphere of your quest and of Avalon.
Finally, you need to package this all up into a single file, with descriptions as to what each piece of text is for, directions for the coding team, and explanations of anything that is non-obvious. Submit this as text file only - no Word documents. Be careful not to use non-ASCII characters (in particular, if you are exporting from Word, make sure it doesn't have mated quotes or long dashes). And don't be offended if your quest once implemented is dramatically different from how you submitted it. We have to consider a number of factors that are not obvious to all mortals, including the overall style of Avalon and the large-scale effects of the quest.