The first thing I do after setting up a fresh Drupal install and creating user id 1 (which I normally name Admin) is to create a second user.

• Go to Administer
• Go to User management
• Go to Users
• Click on the "Add user" tab
• Create your new user

After that I create a brand new role called "Admin"

• Go to Roles in the left hand menu
• Enter Admin into the text field and click on Add role
• Edit the role and check all the permissions boxes

Then I give my UID2 the role of "Admin"

• Go back to Users in the left hand menu
• Click "Edit" beside your second user
• Check off the role of Admin
• Click Submit at the bottom of the page

Then I enable the Blue Marine theme

• Go to Administer
• Go to Site building
• Go to Themes
• Click "enabled" beside Blue Marine
• Go to the bottom of the page and click "Save configuration"

Back to User Mangement I go and I select Blue Marine as the default theme for UID1

• Go to Administer
• Go to User management
• Go to Users
• Click Edit beside "Admin"
• Choose "Blue Marine"
• Scroll to the bottom and click Submit

Log out of "Admin" and only ever use it if there is an emergency--your theme becomes so broken you can't get into any part of the site--or for site upgrades.

After that I use UID2 for my various configuration and adminstration functions.