It really depends what you want to do. Do you want to do networking, system administration, programming, work at a help desk or just build and troubleshoot hardware?
Tech support/help desk type jobs are not like you probably imagine it is. Mostly it's just reading from a script (i.e. telling the customer to reboot) and actual troubleshooting is often discouraged.
If you really want to learn and work with computers you have to put a lot of time and effort into your field of interest. That means reading *a lot* and being able to apply what you read to real problems. Because you need to stay current with the ever evolving technology you need to have passion for technology.
I usually recommend people to check out <A HREF="http://safari.oreilly.com" target="_new"> O'reilly's Safari Bookshelf </A> or <A HREF="http:// http://www.books24x7" target="_new"> Books 24x7 </A> and search for the terms they think they will like. Safari has a free 2 week trial and is a lot cheaper though.
If you want to be primarily a network admin I'd recommend starting with a book aimed at the Network+ and CCNA certifications as you will get an idea of what networking is all about. For system administration start with a book aimed at the MCP Windows Server certification for Microsoft stuff and an introduction book to Linux System administration, for example one aimed at the LPI Level 1 certification. If you want to mess around with hardware go for the A+ certification (and actually get it) and a apply at Fry's, CompUSA or similar places.
The IT job market is in pretty bad shape and certifications are meaningless unless you don't have them. There are almost a million Microsoft certified people out there, so it will not make you stand out to have an MCSE. Nontheless, you won't get a job as an admin if you don't have it. It's the same with CCNA.
In order to start a career in as a sysadmin or netadmin you should try to get in touch with IT people in your area. Look up local Linux User Groups (LUG) and go to Microsoft Technet meetings if they are available in your area. Start talking to people and tell them you are interested in a trainee position, ask questions about books they recommend, courses or classes they recommend and so on. If you decide to go to these meetings you should not be intimidated even though you have no idea what the presenter is talking about, and keep showing up even though it might be boring at first. Who you know is often as important as what you know in landing that interview and job.
Finally, one last tip is to try to get as many interviews as you can even though you are not interested in the job. IT interviews can be gruelling so it's good to have experience when your dream job comes up.
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I want my epitaph to be: "Moved to /dev/null"