If you're speaking of what's considered an operational DBA, there are a few basics:

Backup / Restore:

- Understand the backup / restore options SQL Server provides for you.

- Implement those on your databases to meet your users' needs.

- Test those backups regularly to make sure they are good and to give you an idea of how long the restores take.

Configuration / Performance (OS):

- Understand the various types of RAID and how those can impact your performance.

- Understand how to deploy SQL Server on those RAID configurations to meet cost vs. performance.

- Understand how to measure performance on your SQL Servers (CPU, memory, disk I/O).

- Understand what can cause bottlenecks on those areas.

Configuration / Performance (SQL Server):

- Understand clustered vs. non-clustered indexes and what situations to apply them.

- Understand statistics and how to keep them up to date.

- Understand how to determine when indexes are needed and when they're not.

- Understand how to deploy database and log files to maximize the performance of the disk.

Growth / Capacity Planning:

- Understand how to measure the growth of your databases.

- Understand how to forecast growth over time.

- Understand how to communicate your growth needs to management before it's critical.

Security (SQL Server):

- Understand the difference between users/logins

- Understand how to determine what permissions a login has, down into each database.

- Understand ownership chaining.

- Understand how to get a user the rights that are needed, no more and no less.