2. Get one of the open-source Unixes and learn to use and run it.

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I'm assuming you have a personal computer or can get access to one (these kids today have it so easy :-)). The single most important step any newbie can take towards acquiring hacker skills is to get a copy of Linux or one of the BSD-Unixes, install it on a personal machine, and run it.

Yes, there are other operating systems in the world besides Unix. But they're distributed in binary -- you can't read the code, and you can't modify it. Trying to learn to hack on a DOS or Windows machine or under MacOS is like trying to learn to dance while wearing a body cast.

Besides, Unix is the operating system of the Internet. While you can learn to use the Internet without knowing Unix, you can't be an Internet hacker without understanding it. For this reason, the hacker culture today is pretty strongly Unix-centered. (This wasn't always true, and some old-time hackers aren't happy about it, but the symbiosis between Unix and the Internet has become strong enough that even Microsoft's muscle doesn't seem able to seriously dent it.)

So, bring up a Unix -- I like Linux myself but there are other ways (and yes, you can run both Linux and DOS/Windows on the same machine). Learn it. Run it. Tinker with it. Talk to the Internet with it. Read the code. Modify the code. You'll get better programming tools (including C, Lisp, Python, and Perl) than any Microsoft operating system can dream of, you'll have fun, and you'll soak up more knowledge than you realize you're learning until you look back on it as a master hacker.

For more about learning Unix, see The Loginataka.

To get your hands on a Linux, see the Where can I get Linux.