There are many of Tips & help around the web about joomla. Here are  some tips and tricks links about Joomla!, The best one is Joomla's doc site.

http://docs.joomla.org/Category:Tips_and_tricks

There are som eother good site are also listed bellow:

http://www.alledia.com/blog/joomla-tips-&-tricks/

http://www.dart-creations.com/joomla-tips-and-tricks/

http://www.tm4y.co.za/joomla-tips/

These are very helpful to work  :)