Your keyboard is your friend.
Get to know that sucker! If you plan on sticking around the world of open source operating systems, you are going to use the keyboard a lot. Those files I spoke of above need to be edited. You need to use the keyboard to achieve that goal. Obvious, yes, but it does bear mentioning.
While almost all Linux distributions come with some form of a GUI, Linux is based on Unix. Unix was a command-driven language long before the advent of the GUI concept. In some cases, certain Linux programs can only be invoked via keyboard. While it is true that the more newbie-friendly distributions minimize actual needed keyboard work, it's not completely eliminated! Know your keyboard, and know it well. It can pull you from the fire better than any mouse ever invented.
Every distribution I set up had a forum section on their web site. Contained within those forums are true gems. Sometimes you have to weed through a lot of crap to get to the really good stuff, but you can learn things even as your hands become mired in that crap.
Just as there are different distributions, there are different attitudes when it comes to forum posters. Self-styled computer gurus who feel their fecal matter carries a floral scent dominate some forums; people who are willing to help populate other forums. It pays to check out the forums for your distribution before you make the choice of which one you will use. Believe me, you are going to need to use that forum to fix at least one Linux bug. Why support a forum dominated by rude people?
Beyond the forums for individual distributions, there are also forums for Linux overall, and some of the various and sundry programs within your Linux distribution. There is a wealth of information available at these sites, but generally, there's even more crap through which you must weed. Once again, it pays to weed through some of this stuff, because you can find things out on the way to other things. Personally, my favorite forum for Linux is http://www.linuxquestions.org/ . This particular forum has been invaluable in helping me to fix some of my own issues with Linux problems. The people there are friendly, and are always willing to help. They rock!
Register at the forum for your distribution of choice. Ask questions. Even if those questions have been asked before, there will always be someone willing to answer. Also, as you learn, you can share what you have learned as well. I share often in various forums. To me, that's the spirit that makes Linux what Microsoft offerings will never be: a community effort. The more brains you put to a problem, the more likely that problem will move towards solution. The Linux forums are where those brains get together.
Data is precious. Back it up often.
The most important stuff on your computer is not the files that make it operate. It's the files you create when you use those files. If your operating system goes belly up, it's always a good thing to have the files you created on another form of media, such as a floppy disk or a CD/DVD.
While this should go without saying, and is applicable to any operating system, there are many people out there who suffer great pain when the files they created are destroyed by a crashed hard drive head, or a bad motherboard. The best time to make sure you have copies of those precious pictures, spreadsheets or documents is before the computer goes belly up on you, not after. With the cost of CD and DVD burners and blank media, it's the height of cheap to forgo the ability to maintain a copy of your important work outside the box on which you created it. I back up my entire computer usually once a year. The important stuff, like my music CD projects, get backed up on a monthly basis, or more if I am doing a lot of work with the files in question.
You will know your computer as never before.
Learning Linux means learning what makes your computer tick. That is another Linux absolute. Every form of Windows since Windows 95 has worked to insulate you from your computer. Mac OS insulated you from your computer pretty much from the get-go. Linux does just the opposite. In order to get some things working under Linux, you are going to need to know a bit more about computers than where the CD ROM drive is, or what the CD key is. The more you read the forums, the more you learn. The more you learn, the more you will want to know.
Eventually, you will come to a point where you know the PC's inner workings really well. This is a good thing. Not only does it mean you can fix your own machine, it also means you can fix others. It not only means you can fix your Linux distribution, it also means you can fix Windows as well. If you can get Linux working properly, Windows is a freaking cakewalk!
Don't become discouraged.
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