Download the archlinux iso

dd if=/dev/zero of=/dev/sdb bs=4M
dd bs=4M if=/path/to/archlinux.iso of=/dev/sdb

cfdisk /dev/sda
mkfs.ext4 /dev/sda1
cryptsetup --cipher aes-xts-plain64 --key-size 512 --hash sha512 --iter-time 5000 --use-random --verify-passphrase luksFormat /dev/sda2
cryptsetup luksOpen /dev/sda2 root
mkfs.ext4 /dev/mapper/root
mount /dev/mapper/root /mnt
mkdir /mnt/boot
mount /dev/sda1 /mnt/boot
pacstrap -i /mnt base
genfstab -U -p /mnt >> /mnt/etc/fstab
arch-chroot /mnt
vi /etc/mkinitcpio.conf # add encrypt and shutdown hook to HOOKS. And dm_mod and ext4 to MODULES
mkinitcpio -p linux
pacman -S grub
grub-install --recheck /dev/sda
vi /etc/default/grub # GRUB_CMDLINE_LINUX="cryptdevice=/dev/sda2:root"
grub-mkconfig -o /boot/grub/grub.cfg
passwd # set root password
exit
umount /mnt/boot
umount /mnt
reboot

Post-install setup

useradd -m -g users -s /bin/bash dag
passwd dag
gpasswd -a dag wheel

Other soon-needed stuff

pacman -S sudo firefox ruby vim screen youtube-dl cmus rtorrent wgetpaste nmap lynx mutt msmtp tree offlineimap feh gnupg mplayer pkgfile evince alsa-plugins tcpdump dnsutils whois cups libcups ctags qemu pulseaudio newsbeuter clamav smartmontools ffmpeg base-devel xscreensaver nginx abs ntfs-3g php libreoffice git nfs-utils unzip net-tools markdown dosfstools gparted wpa_supplicant bitcoin-qt imagemagick netcat php-fpm odt2txt openvpn irssi antiword unrar abook iw openldap nodejs dos2unix rkhunter testdisk p7zip sshfs vnstat alsa-utils msmtp-mta strace macchanger hdparm wireshark-cli wireshark-gtk ncrack ispell
visudo # Allow wheel group root access
vim /etc/ssh/sshd_config # PermitRootLogin no
exit

X

pacman -S xf86-video-ati xorg-twm xorg-xclock xterm xorg-xinit

LXDE config

pacman -S lxde
mkdir -p ~/.config/openbox
cp /etc/xdg/openbox/{menu.xml,rc.xml,autostart} ~/.config/openbox
echo 'exec startlxde' >> ~/.xinitrc