I have been using umbraco extensively for the past year and have benefited greatly from the advice and tips from the umbraco community. In the spirit of Christmas I wanted to start my new blog by giving something back, and hopefully help some umbraco new comers in the process!
Clean URLs
Despite being a huge fan of .Net, I still prefer my URL's to be clean and not have the .aspx extension. Luckily umbraco makes this extremely easy to achieve in about two minutes. To start with open the web.config file and look for the umbracoUseDirectoryUrls key and set the value to True.
Secondly open the IIS Manager and go to the application configuration tab.

You need to insert a wildcard map to allow .Net to process files regardless of the file extension. I usually open the .aspx entry in the top box and copy the executable path and paste it when I create the wildcard entry. The only thing to note is that when you create the wildcard entry you need to uncheck the box that says 'check file exists'.
404 - Page not found
It is sometimes easy to overlook the error page that users see, however in umbraco it is very easy to setup. The first step is to create a page in umbraco that you would like users to see when a 404 is encountered. Once this is done look at the properties tab for the page and take note of the page id.

Next open the umbracoSettings.config file in the config folder. In the file you will find a error404 tag. Simply replace the default page ID with your page ID and you are done!
Thanks for the tips, keep them coming!
Useful tips! Thanks (: Lau