After you unwrap your new Raspberry Pi you will need a SD card with a Operating System to boot.
Here is how to get the Raspbian image and install it on the SD card. Also what are the first few things
to tweak your new computer:
Use a name brand class 10 SD card.
I suggest the “SanDisk Extreme” line that is designed for smaller frequent IO
Get the install image from the raspberryPi site here:
I suggest the Raspbian image, since it allows you to change from UK to USA settings and more.
Read the "Howto" install image on SD card from a PC:
First boot of Raspbian the application “Raspi-config” runs you can re-run this to change things.
Take your time and making sure to set things to US or USA since default will be UK settings.
First things you should do once configured is to update the OS:
apt-get update && apt-get dist-upgrade -y
Update the firmware
Install the pre-requists
apt-get install git-core wget ca-certificates binutils -y
Install the update scripts
wget http://goo.gl/1BOfJ -O /usr/bin/rpi-update && chmod +x /usr/bin/rpi-update
Run the update (server usage: 240MB RAM / 16MB Video)
Run the update (desktop usage: 224MB RAM / 32MB Video)
Restart to apply
shutdown -r now
Overclock cpu, sdram and gpu core without increasing voltage
The settings below are only to be used if you have heatsinks installed
echo -e "arm_freq=850\nsdram_freq=500\ncore_freq=450" >> /boot/config.txt
The settings below are safe for all Raspberry Pi’s
echo -e "arm_freq=800\nsdram_freq=450\ncore_freq=350" >> /boot/config.txt
shutdown -r now