1. During Installation, always create swap space and a separate partition for the Home directory. Always select that partition for other Linux distributions also but do not format it. And create separate users for different-different distributions like /home/ubuntu for Ubuntu, /home/arch for arch Linux and so on.

2. If your system has SSD then donot create swap space from SSD.

3. Use Ubuntu Source List generator.

4. Run sudo command without password
If you don’t want to type sudo password again and again then run command sudo visudo and append the below line at the end.

your_username ALL=(ALL) NOPASSWD: ALL

Save using Ctrl + X and Shift + y and press Enter. That’s it.

5. Create user from Command line

useradd --create-home --system --shell /bin/bash --user-group your_username

6. XUbuntu is the best Linux distribution (in terms of performance). It has the power to give a new fresh life to slow and dying old pcs.

7. To Generate subtitles of audio and video, install :

sudo apt-get install ffmpeg && sudo pip install autosub

To generate subtitle :

autosub -o subtitlefile.srt "/path/to/file.mp4 or .mp3"

If you are using Vlc to play the .mp3 file, then you have to select a visualization (Menu > Audio > Visualization > Select any) because Vlc cannot display subtitles without it.

8. Detach a Linux Processes From Controlling Terminal

command </dev/null &>/dev/null &

9. For setting the paths, the file is /etc/environment

10. Reset Mysql Password

11. Auto mount ntfs partitions

12. Change Nautilus Shortcut

13. Fix Duplicate icons for manually created GNOME launcher items

14. Remove unnecessary apps

sudo apt-get remove --purge aisleriot gnome-mahjongg deja-dup deja-dup-backend-gvfs totem totem-common totem-mozilla totem-plugins activity-log-manager activity-log-manager-control-center brasero brasero-cdrkit brasero-common  landscape-client-ui-install unity-control-center unity-control-center-signon empathy empathy-common thunderbird thunderbird-gnome-support onboard onboard-data gnome-orca unity-webapps-common shotwell rhythmbox evolution-data-server evolution-data-server-online-accounts gnome-calendar gucharmap cheese vino gnome-mines gnome-sudoku xdiagnose usb-creator-gtk remmina* remmina-common* remmina-plugin-rdp* remmina-plugin-vnc*

sudo apt-get remove $(dpkg --get-selections | cut -f1 | grep -P "^unity-(lens|scope)-" | grep -vP "unity-(lens|scope)-(home|applications|files)" | tr "\n" " ")

sudo apt-get autoremove

15. Execute sudo without Password
Open terminal and execute command

sudo visudo

Add the below line at the bottom

username ALL=(ALL) NOPASSWD: ALL

Replace username with the username of your system. Now press Ctrl + X then Ctrl + Y and then press Enter.

16. Display full list of startup applications and processes

sudo sed -i 's/NoDisplay=true/NoDisplay=false/g' /etc/xdg/autostart/*.desktop

Now you can open Startup Applications and remove unnecessary applications that starts as ubuntu starts.

17. Enable passwordless ssh
18. Add noatime to fstab
disable last accessed time.