Harden Security and Misc. Tasks for Ubuntu 15+

Remove Misc. Lenses from the Unity Dash:
Note: You may not want to do this if you're new to Ubuntu 14+
sudo apt-get autoremove unity-lens-music unity-lens-photos unity-lens-video

Install Unity Tweak Tools: sudo apt-get install unity-tweak-tool

Install Ubuntu Tweak: http://ubuntu-tweak.com/

Install Preload:
Predicts applications and loads them into memory based on the ones you run the most.
sudo apt-get install preload

Enable the firewall: sudo ufw enable

Secure shared memory space:
sudo gedit /etc/fstab

Add the following line:
none /run/shm tmpfs rw,noexec,nosuid,nodev 0 0

Deny "su" to everyone except administrators:
sudo dpkg-statoverride --update --add root sudo 4750 /bin/su

Secure your Home directory:
chmod 0700 /home/username

Disable guest account access:
echo allow-guest=false | sudo tee -a /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf

Misc. other security tools

• Facebook security checkup tool (more info available at https://threatpost.com/facebook-security-checkup-tool-keeps-tabs-on-security-settings/114039)