When you build a website it is easy to be too involved with it to notice any flaws, be it with navigation or typos. Here are some quick thoughts for you - see how many you are guilty ofASSUME NOTHING
One expression I like is "just because you know how it works doesn't mean your visitor will know."
Remember, you won't be there to explain things to your visitor.Never Assume that your visitor uses the same browser as you.
All of that sounds pretty obvious but all you have to do is surf the net using different settings or using a different browser then you'll notice that a lot of sites assume some or all of the above.TEST EVERYTHING
Testing is critical whether starting from scratch or redeveloping.Navigation
Make sure your navigation is usable and that you can always get back easily to where you came from. Good navigation should not rely on the browser back button.Frames
Make sure all your links target the correct frame. This is especially true of the home link which is normally the frameset document. Make sure your home(frameset) link targets _top and not the content or other frame (seems really obvious but still happens)
If you are redeveloping a framed site to a non framed site then make sure ALL target attributes are removed from your links. Forget to do that then all your internal links will open in new windows which will not impress your visitor.Forms
Test all your forms properly, check every combination - don't assume that the visitor will fill in everything the way you want it. Its really boring on long forms but essential to make sure you get the info you need.
Make sure you test them all again when you upload them - make sure that scripts that process the forms have proper permissions and that the paths to the mail program are correct. Don't assume that because they worked on the development server that they will automatically work when you move them to the live server.Links
Make sure that image paths are correct as well.Test then test again - test the obvious and the not so obvious.
If you have lots of people you can use, get them to test as well - never tell them they are doing anything wrong and never prompt them. Give them small tasks to complete for example. find an article about something or how easy it is to find a certain product or filling out your forms etc.
If you are a one person operation try this - develop your site then forget all about it for a week or so, forget it even exists then, go back and try to use it as a visitor would - sounds daft but it works. You have to be able to remove yourself from it to see the faults.
One last thing to remember - we are all human and we all make mistakes - don't take criticism to heart - be objective about your site not protective. Admit when you get something wrong and fix it, after all who is the site for? you or your visitor :)