1.Study, Understand and grasp firmly the database concepts and architecture.
2.Begin with small project and practice, practice, practice. small projects are good to lear the basics.
3.A good DBA means well experienced DBA. A DBA becomes experienced as the time passes. So first of all you need time. It is in your hands to make shorter this time. Databases shows their dirty sides with the large amount of data and under heavy pressure. So if you want to become a good DBA in a short time :
-Try to read a lot (a lot means realy a lot). Mostly read best practises.
-Examine big queries and their effects on the database.
-Try to work on a database which have a large amount of data with a heavy usage.