This blog posting by Jim Gilmartin talks a lot of common sense about web site design and the content to include.
If you want to get into detail then Nielsen Norman is the place to look, but since most companies don't even get to base on this subject, these pointers will be useful.
My new book digs into the detail of this subject from the perspective of physiological ageing.
Try and encourage your web designers to at least read one of these sets of insights. Dick Stroud