That is a key factor if you are giving individualized advice. See http://www.seclaw.com/docs/RIAOverview.htm If you look at some investment newsletters, you will see that the majority of them are not registered because they do not need to be (and do not want to be because doing so would subject them to additional requirements). The SEC proposed requiring a minimal form of registration of newsletters and web sites once or twice but was beaten back from even a minimal requirement.
that sounds fishy...why would you want to "suggest" to your readers to short a company? ....unless you're trying to gain financially. Don't suggest anything...always offer information that it is to be intended for educational purposes....plus have all of the required disclaimers on the site....but never suggest because it's not in your interest...if so and so loses money on a recommendation then the next thing you know they will be trying to sue for damages not to mention the potential manipulation of the stock's price depending on the size of your readership.....
I believe it's only illegal when you are a license broker and your blog has not been approved by the SEC and also if your blog traders are compensating you for this blog or to receive your trade suggestions. I would definitely check the SEC website though just to make sure.
If you meant that you would suggest shorting one particular company, possibly one where you had some vested interest or conflict, that would be fishy. But I think you just meant that you would be shorting some and buying others, based on ongoing technical/ fundamental analysis or whatever, which would be fine. As a matter of fact there are already such blogs, some by well-known short sellers in the penny stock area, that are quite popular and do not present a problem in general, even those that have fees attached.