First and foremost is the respectably generic answer "find something you like to do and then figure out how to make a living doing it". Which is the approach I took, and it worked.
The bucks are attractive, but if you aren't cut out for the job then you're never going to make it in that profession.
You can make a more than adequate salary in the networking field. Study, take some tests and get your certifications. I know a few guys that can basically tell you how much you will pay them if they work for you.
Enough of that...
If you want a simple database to play with try MySQL. It's quick to set up, simple to work with, and there a slew of free tools to help you manage it. Take a look at phpMyAdmin. It's a web based and easy to work with. Best of all it tells you the commands it is using to do it's job, which makes it a good teacher too.