The biggest mistake that I made when developing some of my web sites was that I used frames in my html. Using frames allowed my website (www.CustomTravelChecklist.com) to show multiple separate .html files on the screen at the same time. I could easily switch the main .html file in the center to show different .html file. Also, I was using javascript and stored session variables in a hidden .html file. Technically, this worked well. However, I came to realize that search engines did not properly index my website. My ranking never seemed to go up. I added a site map and submitted it to the search engines, but that didn’t seem to help too much either. I then did some research on the internet to see if there was some specific SEO (Search Engine Optimization) that I could do for frames. The general consensus was that there isn’t any SEO that would help. I wish that I had known this before building the site. I would have architected it differently. So, if you develop a website, I recommend that you don’t use frames.