Valued Content
Make sure every page in your website has something to offer the reader.
If a page does not offer the reader anything then why is it there, its taking space up you know.
This is an incredibly simple tip, but, a vast amount of surfers who get linked to a worthless page won't browse your site anymore.
That is another lost customer for your new wooden bar-b-que.
Flash, whizy, blinking.
Try your upmost to avoid flashing / blinking text, animated gif's and my big pet hate auto-loading sound.
Animations tend to distract the user on the actual content of the page. Also, if users have slow connections then they will be waiting for them to load and be rather annoyed when they realise what they waited for.
Now I have used scrollers and a bit of flash in my sites so I do not/can not completely condem them, but before you use them just think about the consequences.
At the end of the day, if the client wants animations, scrollers etc (and most of them do) after you have told them for the millionth time and then given into them, try and be tactful. At the end the day I suppose they do pay the bills.
Popup Windows
Now this should be obvious, popups are a big no-no.
I have not met one person that actually likes them, no one likes things being shoved in their face.
Background Images
Image backgrounds do not shout out to the user that this is a professional site. I bet you would find it hard to name a big site that has background images.
Having images on the background also make loading times slower, I know everyone prefers a zippy loading site.
Saying that, if you must do it, make it compressed and make the contrast high so that it does not show out like a sore thumb.
Organise your content
Try to think about what content you have and how it should be organised in your site. If readers are having trouble finding their way around they are not going to stay long.
Click click click
Try to minimize the amount of clicks a user has to click to get where they want. 2 - 3 clicks max.
This is another thing that users find really annoying.
Scrolling pages / Page Length
Try to limit your page length, if a page scrolls on for more than 2 screens you need to consider spreading it over a couple of pages or splitting it into different topics.
The general rule is that users like the information to be nearby, having to scroll is another thing they don't like doing.
Menu
If you have a menu, include in on every single page that you have on your site.
Try to prevent the user from having to scroll up or down to get to your menu, place it in a sensible position.
Frames
Frames are a novel idea, they let you put content onto a site without having to change the entire site every time the users navigates somewhere else.
However, there are some drawbacks to using frames that just make them a big no-no when designing a site.
The address bar does not change when you go from page to page. No user is going to be able to bookmark a page they liked, or more importantly, they are not going to be able to recommend that page to a friend, digg, redit etc.
Search engines do not like frames, they will/could link to the frames content and not the entire site, meaning that users will not see the outer frames contents, not good.
Images
No one likes a slow loading website, the best way to increase loading times is to compress your images.
Try to avoid having image tags like this <img src="mypic.jpg" width="100px">.
Make the image the size you want it in your paint program then add the img tag without the width/height parameters.
One more thing, always add an 'alt' attribute to the img tag. They are useful for people on text based browsers and people with images turned off on their browsers (yep, some people still do this!). They are also crawled by some search engines, so this is a useful place to put your keywords.
Page Size
You may have a great monitor which can handle 1280 x 1024 or more, this is fab for creating sites on. However, remember that a majority of people will not, the last stats produced for this concluded that the majority of surfers use 1024 x 768.
Remember that some people will be also be looking at your site via the phone, blackberry of PDA.
Spelling
This is such a simple thing yet it makes a huge difference to your site.
If someone is thinking about using your service or buying your product and they notice that you cannot spell and be bothered to spell check your website, what image does that portray about you? It only takes a second to spell check.
Links
I have seen many sites with pages of links, the links had no description on them just a big ole url which was next to meaningless.
Now this could have been a link to the cure of the common cold or the solution to world peace, buggered if I knew, and I certainly was not going to click it.
My point is, make your links clear, add a little description so users know what and where they are going.
Another thing, please make sure that your links (if they are internal) do not open in a new window, remember popups!
While we are on the subject off links, try to test your website fairly regularly for dead links, there are loads of tools on the Internet to do this for you.
Colors
Colors are great, they make everything look cool and stand out. Beware however, we are not in the 60's anymore ( I never was ;) ), try to tone down your colors a bit. Nearly all 'nice' looking sites use a great deal of pastel shades that gently blend into one another, calmly and serenely...sorry got a bit carried away there.
Seriously, use your colors sparingly, if you really want to make things stand out, increase the font size a little, make it bold and use a toned down pastel version of your color.
Lets all be nice to our site visitors, they have taken the time to visit your site, lets make it an enjoyable experience.
