One tricky thing about blogging for your clients is that each one brings a different set of knowledge. Someone might want to know how the S&P 500's current P/E ratio compares to historical norms at this stage of an economic recovery; others will want to know what "P/E" stands for.
How do you provide basic information for the latter group, without turning off the former group? Whenever you present something simple, it helps to acknowledge that a lot of people will already know it. "As you probably know, bond yields and prices move in opposite directions." Or, "Remember, the key thing to watch is not the earnings themselves but whether they beat expectations." And so forth.