The best result I've had with Qubes 3.0 (stable). I've choosed KDE only installation. For beginners I do not recommend installing Qubes-R3.1-rc1 yet as it has some bugs (e.g. it must be installed with "user' as username to avoid errors in installation) and networking doesn't work out of the box.
1) Download Qubes-R3.0-x86_64-DVD.iso and copy ISO to 8GB USB stick (Change /dev/sdX to your USB stick):
umount /dev/sdX; dd if=/path/to/Qubes-R3.0-x86_64-DVD.iso of=/dev/sdX bs=16M; sync
2) Boot and install Qubes from USB stick. Press F10 for Boot Menu or F2 for BIOS. If selectable choose the boot device without UEFI.
3) To avoid an unbootable system do not press the reboot button after installation is finished! Change to console with Ctrl-Alt-F1 and reinstall Grub first:
grub2-install --modules=part_msdos --boot-directory=/mnt/sysimage/boot /dev/nvme0n1
If you already rebooted you can also boot again from USB Stick and choose Troubleshooting - Rescue Qubes System and reinstall Grub from there.
4) After updating x11 drivers on Librem 13 I've had freezes at the lock screen so do not update as recommended . Just connect to Internet & update dom0:
sudo qubes-dom0-update --releasever=3.1 xorg-x11-drivers xorg-x11-drv-intel
5) Update all Template and Standalone VM's in Qubes VM Manager. Do not forget to shutdown the Template VM (e.g. fedora-21) and restart the depending VM's.