Have you thought about the right Data type which you should use?
Is VARCHAR bad? Do you review the SQL statements that you have written? Do you know what sort of impact indexes produce? How to leverage the query Caching techniques? Do you follow the naming standards?
This simple slide teaches you the best mySQL practices to be followed up by 15 minutes.
Taking out the best from mySQL will improve the application performance if its part of your day to day life get into these standards and practice this every day. This presentation from Ronald Bradford. Thanks to Ronald for sharing.