Initial Configuration using the raspi-config utility.
The first time the Raspbian system is booted a menu type utility will automatically run. (raspi-config). This utility will help you get some basic configuration taken care of.  The utility may be a bit '90's 'DOS' like, but believe me it is way easier than trying to do these tasks manually.
Note: These configuration settings can be done now or you can wait and do them later at anytime. But remember that after the first boot, this utility will no longer automatically run. To run it again you  need to type this command at a terminal prompt:
    sudo raspi-config
Use [Tab] or [arrow keys] to navigate, [Spacebar] to select / un-select, [Enter] to choose.

Note the raspi-config utility is only available when using the Raspbian OS.

Raspi-Config Main Menu
Raspi-Config Main Menu

Raspi-Config Settings
A brief explanation of selected options:

1. Expand Filesystem:  (
Expands the OS partition to fill SD card):
This option is already done if you installed with NOOBS. If you installed Raspbian using the 'raw' image method then you will need to do this option as soon as possible.

2. Change Password for user pi:
Everyone knows your password unless you change it. Please remember your password. Difficult but not impossible to recover.

3. Enable Boot to Desktop / Scratch:
Allows you to choose between 3 booting options.
  1. Console Text Console - The default setting will boot to the Command Line Interface CLI. After login you must use do startx command to get to the GUI.
  2. Desktop log in.... - Skips login and boots directly to the GUI desktop as user pi.
    Note if you want to have the GUI automatically start but you still want a user/password login prompt then see below.
  3. Scratch - Boot directly to GUI Scratch program. Scratch is a basic graphical programming tool.  Do not do this option unless you know you want to boot to Scratch each time you start the system. Note that Scratch can be run from the regular desktop.
     If you have set boot to Scratch and want to change back to desktop or console then do this:
4. Internationalization Options: (3 options)
  1. Change Locale: (Default is en_GB.UTF-8 UTF-8) Use cursor keys to scroll through the entire list and select [*] or unselect [ ] using the [Spacebar]. (US users should use: en_US.UTF-8 UTF-8). Be sure to unselect any you don't need. Once you press OK, you will be given a list of Locale(s) that you selected in the previous screen. Highlight the 1 selection you want then press OK. Be sure to move the highlight off of None or you will get...... None 
  2. Change Timezone: You must specify your local timezone. Note that the system will automatically get the time from Internet when connected but has no way of knowing which timezone you are in unless you specify here.
  3. Change Keyboard Layout: (Default is English_UK). US users, or anyone using a US keyboard, will need to change the keyboard setting. If not some keys such as # will not work correctly. To change from UK to US  select [Change Keyboard Layout] and do this:
    • If your exact keyboard is not on the list then choose one of the generic 101,102, 104 -key etc.
    • Scroll down and select [Other] to get to the country of origin menu.
    • On country of origin menu select: English (US).  You will now be at the keyboard layout menu.
    • On Keyboard layout menu scroll to top and select: English (US). Note: Do not select anything else on the list unless you know exactly what you are doing!
    • A reboot is required to make changes stick.
5. Enable Camera:
For the Rasberry Pi Foundation CSI camera modules only.

6. Add to Rastrack:

Don't know why this is here?

7. Overclock:
Use to overclock or make the system run faster. Note that the RPi is not guaranteed to work when overclocked. If you experience system hangs, crashes and/or SD card OS corruption then choose a slower setting.

8. Advanced Options:

A1. Overscan
- Use if you have problems with boarders on the screen.

A2. Hostname - (Defualt raspberrypi) Like computer name in Windows. If you have more than one RPi on your network then you may want to make each one unique so you don't confuse them.  The Hostname is shown at the command prompt pi@raspberrypi ~ $. When choosing a name be sure to follow the conventions shown on the Hostname screen - no spaces etc. If you don't have a proper hostname then the system will not work properly.

A3. Memory Split - (Default 64 or 128 with camera enabled) Defines how memory is to be allocated between the GPU and the CPU. Entering a value of 64 means GPU will use 64MB and the CPU will use the remaining (448MB). The GPU setting cannot be set any lower than 16. If you don't use the GUI or run 'headless' or run a NAS server or similar, then use 16. If you use graphic intensive applications,  play movies, then a higher setting will be needed. You may need to experiment to get the best setting for your needs.

512 MB RPi 256 MB RPi
16/496 16/240
32/480 32/224
64/448 64/192
128/384 128/128
256/256 -

A4. SSH - (Default enabled) Remote connection to the RPi text console from a remote computer.

A5. SPI - (Default disabled)

A6. I2C - (Default disabled)

A7. Serial - (Default Linux console on serial port enabled) Choose no if you want to connect a GPS or other seial device to the GPIO serial port.

A8. Audio - (Default Auto) 
 3 choices
  1. Auto
  2. Force audio out the 3.5mm jack.
  3. Force audio out with the HDMI.

A9. Update - Let the normal update process handle this.

Other configurations not in raspi-conf:

Automatic start of GUI with login (username and password prompt):
  1. First if not already done, you must set boot to desktop then reboot.
  2. Open a LXterminal then do:
    sudo leafpad /etc/lightdm/lightdm.conf
  3. Find this line: (approximately line 78 in file)
  4. Comment out this line by inserting a # like this:
  5. Save and exit then reboot.
Note: If you ever go back and do set to desktop with raspi-config again, (Step 1), then the changes to lightdm.conf will revert back to the default (no login). If so simply redo the edit again - (Steps 2-5).

Sound Configurations and Hints

 The set volume and mute controls:
        sudo alasamixer

The following can now be done with the raspi-config utility

Default mode auto sound:
       sudo amixer cset numid=3 0

To force sound out the audio jack:
       sudo amixer cset numid=3 1

To force sound out with the HDMI:
      sudo amixer cset numid=3 2

Note that there is a space before the last number in each command....... numid=3[space]0

To play a wav file from the command prompt:
    aplay filename.wav
    aplay /usr/share/sounds/alsa/Front_Center.wav

To get MP3 playback:
      sudo apt-get install mpg321