How to get into the hacker mindset
Disclaimer: Read this for the entertainment value and see if you can use any of the information. I do not claim to be an expert or something. Well, maybe I am an expert breather, because I seem to do that very well, but that is completly beside the point.
Question your motives
Very often we, as human beings, think we want something or crave something just because we are mistaking it for something else. If you want to become a hacker, you might already be on the wrong track. Don't get me wrong - this isn't one of the "If you aren't born in the USA, you'll never be president there" speeches. I am just making the assumptions that your motivation as to why you want to be a hacker might differ from how hackers define themselves. Do you want to totally baffle your friends by taking down their machines during a match? If the answer is yes, then you don't want to become a hacker, you want to become a better jerk.
Do you want to show that pesky corporation the full amount of your wrath by defacing their website? It hasn't been en vogue for quite some time, and yes, you're thinking about becoming a better jerk again.
Would you like to tinker and/or use programs and other stuff in a new and peculiar way? Do you take stuff apart to see how it works and put it back together in true Frankensteinian manner to accomplish new things? Are you curious about how stuff just works? Congratulations, at least that is the kind of mindset which a lot of hackers and affiliated people share.
(Dear hackers, for the sake of simplicity I am sometimes writing about "hackers", as if we all had some things in common without any exceptions. We are, of course, all individuals [except Dave, he's a total clone] and I try to avoid generalisations as much as I can).
Define your interests
I personally do not think that one has to be the best in a field to show interest in it. On the contrary, learning somehting new is easier in any field where one hasn't any knowledge or preconception. But since it isn't about just learning anything new, pick something that interests you - be it crypto, hardware hacking, malware analysis, web application security or any other field you like. Use the tools you know or challenge yourself by using a new toolset like a new language to accomplish your goals. If you can't really define your interests at this point, no worries. You don't have to. This little guide is meant to get you started - it's not a dogma to follow. (In fact, adhering to strict guidelines might be seen as detrimental to getting into the hacker mindset.)
Starting your adventure
Start local, think global, act local
Now what do I mean by that. Depending on your country of residence, hacking might be an illegal activity - especially if you target hard- or software you don't own without permission. Most countries have laws in place that would seriously increase your chances of getting into conflict with the law when hacking. Before you download software, buy specialized tools or hardware and the like, find out if what you're about to do is legal wherever you are right now. Take lockpicking, for example - many Western countries have no objection to people carrying their case of lockpicks, but it could get you in jail in Hungary - even if you are a professional locksmith. (That's what Wikipedia says)
It might be the same for other stuff, so check - knowledge is important.
So generally speaking, look at the stuff that's happening in the world and try to recreate setups and the like in your virtual test lab at home. Speaking of which, an article on how to set up your test lab will follow shortly...