HTML5 video is set to become the next standard for displaying videos on the web and naturally, you should offer both a way in which users can stream your content through an HTML5 format as well as another format such as flash for those who have an older browser version.
Make sure your site passes the NoScript test. Download and activate the NoScript extension for Firefox and see if your site is still readable. Some content, such as ordering systems for products, can't work without scripts, but if your site is simply blank with scripts turned off, that's bad news.
It may look pretty, but stay away from having too many animations on your site. Having your sales splash page rotate, spin and blink may look cool to you, but it will likely drive potential viewers away. When you add too many flashy splashes like that, it makes your site look amateurish which is not the message you want to convey.
Separate your topics. If you have several topics of discussion on your site, put them on different pages. This helps alleviate any confusion that your customers may experience, as well as giving search engines a broader and more clear view of your site, potentially bumping you up higher in their rankings.
The 90s called. They want their web frames back. Frames were of great use in the early days of web design, but it had a lot of flaws. Frame designs make it harder for readers to bookmark your site and scrolling becomes a chore. You can use much simpler methods to allow your users a way to navigate your content.
Try to code using only CSS. We're moving away from table-based sites to only CSS sites because they are reusable, accessible, and they can greatly reduce your file sizes. This allows you greater control of the appearance of your site. There are various CSS resources you can use, therefore, knowing CSS is invaluable to web design.
Never bite off more than you can chew by attempting to design multiple sites at once. You should keep things simple by only working on one site at a time. Even if you do have some web design skills, you may get crossed up with your projects, or one of your sites may suffer neglect. Just take things one at a time.
Now that you've learned some of the ins and outs of web design, you should, hopefully, be a bit more eager to use it to your advantage and gain a reasonable amount of profit through it. Web design is the future and now you have a good idea of how to become good at it. Use this to your advantage and become successful for years to come.