1. All distributions have a "wiki" - a source of online information. If you have any problems, search the wiki first for solutions. If the wiki doesn't have the information you need, or you can't understand the information, try asking on a forum.
2. Remember, software is best installed from your package manager, rather than through just downloading stuff from the web.
3. Your Linux desktop is quite functional even if you haven't turned on 3D accleration, Compiz, a dock, etc. If you're having trouble understanding how to do those things, then don't worry too much. With time, you'll learn enough about Linux to do this.
4. If a Linux live CD doesn't boot up on your computer, try adding extra kernel options. There's usually a key you press at the boot menu that allows you to edit the kernel options. Press this, and remove the "quiet" and "splash" words, then add "noapic acpi=off irqpoll" to help Linux to load on incompatible hardware.
5. If your wireless card is reported to be useless on Linux, look at the websites of some local computer stores. Look up online what cards from those stores work with Linux out-of-the-box, and then buy one.
6. Instead of using Wine to shoehorn Windows programs onto your desktop, run native Linux programs. Amarok will definitely run better than emulated iTunes, especially if you want to put music onto your iPod.
7. On the topic of iPods, DO NOT BUY ONE. They currently all work with Linux, but when Apple introduces new models they build them to stop them from working with non-iTunes programs. There are better and more Linux-compatible MP3 players around.
8. DON'T compile new versions of key libraries unless you REALLY know what you're doing! You could introduce instabilities, break the GUI, or even plain stop the computer from booting. I once compiled a new version of libfreetype so I could use a bleeding edge program, and broke all GUI programs... luckily I knew how to fix it.
9. If you're using Ubuntu, go to www.medibuntu.org and follow the steps to enable the Medibuntu repository. It makes restricted formats so much easier to install.
10. Contrary to popular belief, Linux is very easy to use. It just does most things completely differently to Windows or Mac OS. If that scares you, consider buying a computer with Linux preinstalled, or go to an "Installfest" at a local Linux User Group to have Linux installed for you.
When creating swap, use this rule: RAM<256 set size at 512. RAM=256-512, use value of 1 to 1.5xRAM. RAM=512 to 1G, use va;lue of 1G. RAM>1G use 1G.
Limit the /tmp and /var folders to a max size 512M.
If you are into graphics and designing, have a simple desktop. Xfce is one with an easily accesssible menu.
Disable services that you don't need through the administration interface or through xinted or inetd.
Iceweasel, Bon Echo, Firefox, Seamonkey- all the same- are memory hogs. Tweak them. Use another browser when posible.