Check your 3DS system version in System Settings
Make sure the console is charged and has a working SD card
Back up all SD card files to a computer
Visit the 3ds.hacks.guide website
Follow the guide for your exact 3DS model and system version
Use the recommended exploit method from the guide
Prepare any required files on the SD card exactly as instructed
Copy the needed homebrew starter files to the SD card
Insert the SD card back into the 3DS
Launch the exploit method from the guide
Install boot9strap and the required custom firmware files as instructed
Complete the final setup steps from the guide
Reboot the system and confirm custom firmware is working
Install the Homebrew Launcher and any homebrew apps you want
Keep the guide bookmarked for future updates and troubleshooting