Life saving modules:
Stop downloading, uploading unpacking modules: get Drush - a command line for Drupal. And because you'll hopefully do your development locally and migrate to a cheap server with no shell access Backup and migrate is just the ticket. It has the added benefit of instant protection when you go slightly crazy and decide to start hacking directly at the database at 3 in the morning because CCK import is not working, and it will"save time". Use it with drush and backing up the database is as easy as "drush bam backup."
And also admin will save time and make your backend look good. Which is always a bonus.
Other stuff you will forget to do:De-bug for IE6. Strange as it may seem the Statcounter global stats indicate, millions of people are still using a browser that was released in 2001. This was practically before the internet was invented. So you'll need to make sure that your site at least functions: http://www.my-debugbar.com/wiki/IETester/HomePage, even if it doesn't look pretty: http://ipinfo.info/netrenderer/
And lashings of tea.