DO NOT try to UPGRADE or add major software to the USB "live" session. Also, DO NOT download big files while in USB "live" session. If you do, your USB casper-rw "persistence" save file will run out of space and Elementary Freya will stop working. If this happens, you can either (1) replace your USB /multiboot/Elemenary-Freya/casper-rw file with a backup file or (2) delete your broken casper-rw file and start up with a barebones non-persistence (no save) USB session.
If you install to hard disk, one of the first things to do after first bootup (only in a "Hard Disk" session) is to UPGRADE.
In TERMINAL (hard disk only):
> sudo apt-get update
> sudo apt-get upgrade
I have customized this USB "live" session to make it more useful and fix some bugs. You may want to do the same after installing to hard drive.
From the Applications Menu, here are the first things I did after installing to USB:
1. SYSTEM > POWER > TURN OFF SCREEN > NEVER
2a. SYSTEM > DISPLAYS > blue configure * > 1024x768 or 800x600 > Apply > Keep
2b. SYSTEM > DISPLAYS > blue configure * > 1366x768 (or maximum) > Apply > Keep
3a. FILES > FileSystem > CDROM > DISTROS > right-click to COPY eos-wallpaper-[red|blue].png
3b. FILES > HOME > Pictures > right-click to PASTE
4. DESKTOP > PICTURES > click on eos-wallpaper-[red|blue].png
From Application Menu TERMINAL
> sudo add-apt-repository ppa:mpstark/elementary-tweaks-daily
> sudo apt-add-repository ppa:mc3man/trusty-media
> sudo add-apt-repository ppa:me-davidsansome/clementine
> sudo apt-get update
> sudo apt-get install elementary-tweaks
> sudo apt-get install ubuntu-restricted-extras ffmpeg gstreamer0.10-plugins-ugly libavcodec-extra-54 libvdpau-va-gl1 libmad0 mpg321 gstreamer1.0-libav
> sudo apt-get install vlc
> sudo apt-get install mtpaint
> sudo apt-get install gedit
> sudo apt-get install clementine
1. APPEARANCE > CURSOR > redglass
2. APPEARANCE > WINDOW CONTROLS > Windows
3. SLINGSHOT > Columns = 5
4. TERMINAL > Theme: Monokai
5. PLANK > Icon Size: 38
6. PLANK > Theme: Transparent
From Applications Menu > SYSTEM > Applications
1. Web Browser - Google Chrome
2. Video Player - VLC
3. Music Player - Clementine
4. Text Editor - Gedit
From Applications Menu > drag icons to PLANK (dock)
1. Google Chrome
2. Clementine
3. VLC
4. mtPaint
Right-Click on these icons to UNCHECK "Keep in Dock" (to remove)
1. Midori
2. Music
3. Videos
From Applications Menu > System > Tweaks
1. Plank > Screen Position: Left