The following eight mistakes are ones that people online frequently make. In no particular order:

1. Do not use a different photo on your social media profiles.

For example, do not have a professional photo on your LinkedIn profile with a link to your Twitter account that has a photo of you in sunglasses. You want a consistent professional image across all social media platforms.

2. Do not use a Gmail or Hotmail address for professional purposes when you have a professional email address.

For example, do not have a Twitter background displaying your business’ website URL and a Hotmail email address instead of [yourname]@[yourdomainname] email address.

3. Do not use offline marketing material that sends people to an unprofessional website.

If you are promoting a professional service or business, your image will be impacted by what people first see on your website.

4. Do not have a website that is completely Flash.

A Flash home page can discourage people from staying on your site. And then having to wait for Flash to load for every additional page can really drive people off your site.

5. Do not use references in your posts or articles to a specific date if you want the articles/posts to be evergreen (not to appear dated).

For example, do not say “Today, in 2011,…” when you can say “Today, in this era of online marketing,…” (Yes, sometimes the date will be important. But when the date is not important, do not include it.)

6. Do not use a period to end a sentence if the period immediately follows a link.

If you can’t rewrite the sentence to put the link elsewhere in the sentence, leave off the period. Many people mistakenly pick up the period when they copy/past a link – and then, of course, the link doesn’t work. (See recommended usage in bio at end of this post.)

7. Do not be penny wise and pound foolish when it comes to your online presence.

If you have an older website that is not social-media friendly and search-engine friendly, walk away from it. Either use a Facebook Page (NOT your Facebook personal profile) as your website for now, or get an effective website.

8. Do not link to Twitter from your LinkedIn profile if you only tweet once every week or so.

This is not an effective use of Twitter and there is no reason to showcase this to people reading your LinkedIn professional profile. Better not to have a link to Twitter than to link to an ineffective account.

In conclusion, everything you put online reflects on you. If you have a business, you want to reflect well on that business.

And NEVER EVER put anything online – regardless of what the privacy controls supposedly are – that you would be upset to have your mother, your client or your boss read.