If you start placing building blocks on a bad foundation, you'll likely be making repairs before you're finished. Save yourself the frustration of hunting down errors later by making sure they're fixed from the beginning. A little extra time now will leave you much more time in the future.

Readme.txt and documentation is your friend. Follow the steps carefully to ensure a good install of any extension.

Make sure you are using the latest version. Subscribe to the Joomla security thread to know when important Joomla updates are released.

Seeing red? If you see red when you are installing Joomla, fix it BEFORE the install is finished. You'll love yourself later.

Read the Requirements! Every extension has requirements of some kind. Make sure you read them and have what it takes.

You're off to a good start!