Surprisingly on of the more frequent forum questions here at SQLServerCentral is from technical professionals who either by choice or circumstance now find their career direction on the path to becoming a SQL Server DBA, but don't know how to learn the skills that they will need, Well, look no further, because in sixty seconds or less, the following guide will show you how to go about learning the DBA skills that you will need.
Get SQL Server Developer Edition, either 2005 or 2008. It has all of the features of Enterprise Edition, but you can get it for $65 or even less. If your employer wont buy it for you, then pay for it yourself.
Familiarize yourself with BOL (Books Online, SQL Server's Help system). Even without your own SQL Server installation, you can still use BOL free at MSDN's website (both 2005 and 2008). BOL will be your best friend throughout your career as a DBA.
Try to get your company to send you to training. This is hugely helpful, so keep coming back to it as often as your boss will tolerate it.
Start to study for the certification exams. Not those "cheater" aids, they're worthless if you really want to learn the material. Instead get the Microsoft study guides, and the self-paced learning kits for the exams. Don't worry if you don't know any of the answers at first, just study through them and learn the answers.
Simultaneously with four, above, start to follow the forums here, or at Ask.SqlServerCentral.com. Try to figure out the correct answer to each question (in "Administration") by using BOL and your SQL Server (try stuff out). If you cannot figure it out, don't worry, read the answer(s) in the thread and then try to implement them yourself. Read BOL and try to understand why it's the correct answer. If you don't understand why then ask questions.