1. Navigation: Ensure that your navigation is easy to use and consistent. You may be able to use it, but could a newcomer find the information they desire?
2. Sound: If you have repeating background sound, music or ambience get rid of it. Most users browse in a work environment and as soon as they hit your site they're not looking for the content, they're looking for the "stop sound" button.
3. Click here: Why? Change this phrase everywhere on your site. It doesn't make sense out of context. The user has to read the whole paragraph (which they probably won’t) to understand why they should click there. Consider phrases like "Download the pdf" or "view the full information listing."
4. Title & Alt Attributes: Use them how they are supposed to be used. If you haven't used any at all, then a quick fix will be to start adding them to navigation and other elements on every page.
5. General: If you’ve got any code snippets that could annoy the user, like resizing browser windows or opening new pages in a new window, then remove them. Just because you like something a particular way, your users may not. Don’t take over their desktop.