If I don't use specific sources, I like to add an "read more about this topic here" section. That's often enough to make the post more credible, especially when it's just the basics.
Always remember: what's basic knowledge for you might be completely unknown for someone else.
Concerning long posts I recommend splitting them up in several parts, that's usually easier to digest for the reader.
Of course, the 1000 words maximum is just a suggestion. Not everyone will stop reading at this point but shorter posts attract a wider audience.