Top 7? Weird number huh. I want to make it top 10 but don't have 10 things that I feel are essential for every linux user. Please send your suggestions to me.
Keeping a notebook is the best peice of advice that I've ever received. I keep all of my hardware specs and major system configuration changes in here. Its good to know the most intimate details about your hardware without having to go through the books that came with your system. Nowadays, the stuff you need to know isn't documented in your OEM book and the net is the only place to find the necesarry information. Trust me, you need to have a notebook! There is zero to no chance you will remember that magical command you used to get your cheap-o onsale peripheral to work again. I even keep neat non-tech-but-I-didn't-know stuff in mine.
The website for your particular distrubtion contains indespensible information specific to your system. This stuff is directly from the people who put out your system. You will see announcements of new and exciting things as well as find fixes to bugs that were found after your CD was burnt.
These things are great sources of info that can answer 90% of your questions. Take a gander over at http://www.linux.org/help. It has links to the Linux Documentation Project (LDP) and other places to look when someone tells you to RTFM (Read The Fine Manual). Web tools like dejanews and AltaVista are great places for answers too.
This is necessary to manipulate your system's software. Red Hat, Caldera, WGS, and SuSe users can check out my rpm article. Sorry, at this time we don't have any local info on Debian's dpkg. Debian users can test out the previous point. :)
This is one of the greatest parts of linux. Everything is customizable. This is a good thing because it allows you to make the system work for you instead of the other way around. The other benefit to customization is you will become an expert in the software you decided needed adjusting.
A few suggestions are:
Its good for everyone to know their resources and find answers on their own. Sometimes you just get stuck. It happens to the best of us. If you feel you've gotten to this point, then ask! Lots of us enjoy helping out.
There will always be someone ahead of you and someone who knows less than you. Free software is built from teamwork. It involves designers, coders, documenters, and general users. Each group is equally important and each group needs help. Linux is cool because it continuously gets better!