Those are some useful tips for web designers , hope that it will help you :
10 - Try to avoid using flash and rich-media content to present your information. Search Engines cannot read through video clips, pictures or flash banners.
9 - The website belongs to your client, so take the time and visualize what he wants rather than what you want to give him. Your job is to turn his dream into a reality, not make him accept your dream!
8 - Cross-browser compatiblity is a must. If you’re serious about your craft, you need to take the time to test your creations in different browsers. Just because you’re using Firefox, it doesn’t mean everyone is. Also, always validate your code! http://validator.w3.org is a very good start.
7 - Most people read from left to right. Put your important information to the left of the site.
6 - Stick to a color theme. Take your time and analyze color swatches and see which colors match which don’t.
5 - Yes, SEO is important, but think of who the website is aimed at. Your users! Many people overdo keyword injection into their content to drive up their rankings forgetting the fact that it’s the users who are READING your site not search engines. SE’s are just crawling it.
4 - Give relevant information to the topic at hand. Don’t confuse users with a bunch of topics all at once. Make your content structured and easily reachable.
3 - Leave adequate spacing between elements. A website packed as a pack of sardines is confusing and not pretty.
2 - Keep your writing short and concise. You’re writing in a fast-paced medium where most people if they don’t find relevant information to their search within seconds, they leave. You’re writing on a website, not a novel.
1 - Less is more. If you think that an element is cluttering the page, then it probably is. Get rid of it or find another way to present it.
Finally, I’m gonna mention 2 indispensable tools for web designers. These are 2 addons for firefox that help you diagnose problems on the fly and correct them. Saves you a lot of time and will help you visualize errors.