Before you begin writing, or whenever you read this, you can go online and see what resources are already available. I recommend this and I do it. It is very useful for getting started with any project.
Search the Internet
If I am going to be teaching a topic I have never taught before, I go online looking for the subject. I add key words such as “teaching,” “lecture,” and “study questions.” (Study questions tend to take me to resources such as Sparknotes or Cliff Notes, but that is useful because it lets me see what the students might find helpful.)
Links
Look for links which have already done what you are doing. You can use them as references or as supplemental information.
Links post
You obviously don’t want to simply direct someone to a useful source, unless you are creating a list of weblinks. Even then it is useful to add your own evaluative comments. (Say what is good and bad about the source.) Especially note any unique information or information which is presented in a unique manner. (An example of a weblinks post.)
Evaluating Web sources
If you aren’t sure how to evaluate a website to see whether the information is reputable, Berkeley U has a source called Evaluating Web Pages: Techniques to Apply & Questions to Ask.
Analagous sites
Also, look for sources that do something like what you are doing. If you are going to write a new member’s guide to a gym, then it would be helpful to look at other new member’s guides, both for gyms and other things. If you are writing a user’s manual for software, you can look at older versions’ manual or at other manuals for similar software.
Nothing available?
If there are no online resources, then you might consider posting your work when it is done, making it available for someone else. You will have contributed to the shared knowledge accessible via internet and become a part of the web-based learning community.
This will involve you in the third industrial revolution (new technologies), according to Binde of UNESCO. Haven’t you always wanted to be part of a revolution?