Redirection –URL redirection should be avoided as far as possible. The user feel cheated when he clicks any url and he redirects to completely different content or site.

Blog Community Widgets — I personally don’t like the community widgets provided by blog communities like mybloglog.com or blogcatalog.com. They increase the timing of the page loading and also diverts the attention of the user from your site.

Different Design for subfolders — Suppose you are running a community portal. It has forums, blogs, chat rooms, photo gallery. You are using different scripts for them and they are installed in different sub-folders. I know it is difficult to use same theme, look and feel and design for them but at least you should try to keep at least the same logo and background for all the modules.

Dark Colors in theme or background. — Avoid use of dark colors, they are only better for porn and gambling sites. For instance, every product of google is using light colors as they better for eyes and on such sites with light colors user can spend maximum of his time.

Page Loading — Loading of the page should be very fast so that user should not wait and watch for your content to load. It is very essential for the success of any site. I can give you example of google, it’s search results are not much different from that of other search engines but the thing that matters is the fast results that google gives on searching any keyword. Clean your pages removing large picture (especially .bmp files), video, flash etc files.

Banner ads — Unnecessary banner ads diverts the attention of the user from your website. So do not use banners ads more than 1 or 2.

Small text or improper font — The font size should be standard i.e medium. It should not be too large or too small. Also, the background color should be completely different from the font color.

Difficult Navigation and menus– The purpose of page navigation is to give users a way to keep track of their location within programs or documents. Page navigation should be dynamic and show the path that the user has taken to arrive at a page. Always try to give important links in the menu, don’t flood your menu with unwanted and external links. It is a bad practice.

Unnecessary use of technical jargons — People are getting confused and don’t want to deal when website developers use to geeky language, technical terms etc. So it’s better to keep the language of the site as simple as possible so that even a layman can understand. Simple and clear language should be used for writing blog articles.