Upgrade RAM to 32GB+
Upgrade storage too, if necessary
Wipe storage, install Arch Linux
If this is my insecure laptop, turn off all mitigations (spectre / meltdown, etc).
Custom compile Linux Kernel with my selected patches and build parameters (like LTO), mostly taken from other projects like Xanmod.
Install particular proprietary drivers (nvidia-dkms, etc)
Setup X11
Install all my required 'base' packages, like fonts, tools, and Fish shell
Clone all my dotfiles
Clone my customized window manager, terminal, and menu (dwm, st, dmenu). Build them and install
Install Firefox with custom configuration to increase privacy and remove Mozilla crap. Install my plugins. Install my greasemonkey scripts.
Install my custom written DNS over TLS proxy, remove the system DNS software (systemd-resolved). Why? Mine is better for my purposes.
Pretty much done, I then use a script to install all my misc software for development.