There are several steps to hiding your letterbox. First, you should make sure the container you are going to use is waterproof and weather resistant. Just in case moisture gets in anyway, put each item going into the letterbox in its own zip top bag. Every letterbox needs a logbook, a stamp (preferably a unique stamp carved for that letterbox) and probably an ink pad. Other items are optional.
Pick a hiding spot for your letterbox. You want your letterbox to be well hidden and unobtrusive, but at the same time you should avoid harming the surrounding area while hiding it. Once you've hidden the box, you can start working on clues. It's a good idea to work your way backwards from the letterbox to an area you think works best as a starting point -- this can help you create better clues. The clues don't have to be easy, but they should make sense and have a logical solution that leads to the letterbox.
Once you've hidden the letterbox and worked out your clues, decide on whether you want to create any puzzles or riddles from your information. Check your work carefully for any inaccuracies and then post it to a letterboxing Web site. Before long your letterbox's logbook should have a collection of stamps from enthusiastic hobbyists.
It's important that you maintain your letterbox after you hide it. Sometimes a letterbox is dislodged due to weather, animal interference or human intervention. It's always possible that someone mistakenly thought the letterbox was trash, or that a previous letterboxer didn't return it to the proper hiding place. You may also need to add a new logbook if the existing one has run out of empty pages.
If for some reason you need to remove your letterbox, you should notify the Web site you use so that people don't keep looking for something that is no longer there. You may have to remove a letterbox if it is damaged or if too many people have visited the area, putting it in danger.
In the next section, we'll look at the rich language of letterboxing, and what all those crazy acronyms on letterboxing sites mean.