Problem: “WARNING: untrusted versions of the following packages will be installed!”

sudo apt-get clean
sudo rm -rf /var/lib/apt/lists/*
sudo apt-get clean
sudo apt-get update 

Solution from: http://serverfault.com/questions/444798/debian-warning-untrusted-versions-of-the-following-packages-will-be-installe 

Problems with bluetooth file transfer

"gdbus.error.org.bluez.obex.error.failed" "unable to find service record"

Try killing obexd

To configure cheese and other applications

Use dconf-editor

To install XCTU (Windows version) on Linux

This is a good tutorial about this.. https://github.com/TauLabs/TauLabs/wiki/Xbee-Programming-on-Linux

However, this is no longer needed because XBee has a Linux version now :D

Anyway, I post this because I think it could help to install other similar windows-based software which needs to connect with usb (serial) ports.

Solution for the problem "skype: error while loading shared libraries: libGL.so.1: cannot open shared object file: No such file or directory"

Source: http://askubuntu.com/questions/555902/problems-after-installing-skype-4-3

Execute: 

LD_PRELOAD=/usr/lib/i386-linux-gnu/mesa/libGL.so.1 skype

Turn off or modify Cheese snapshot sound....

 One solution is to modify the file /usr/share/sounds/freedesktop/stereo/camera-shutter.oga

Solution from: http://unix.stackexchange.com/questions/93368/how-can-i-disable-the-shutter-sound-of-gnome-screenshot

For installing nvidia drivers in various Linux distributions

An excellent link: http://www.tecmint.com/install-nvidia-drivers-in-linux/