The whole system first — what it is for, and the subsystems inside it.
Tell us about your environment and we'll generate customized installation instructions.
We ask you to use your own SQL Server: your DBAs already back it up, patch it and encrypt it, and your own licence gives you encryption at rest and room to grow. The bundled Express is there if you would rather not — free and licensed for production, but capped at 10 GB per database and with no encryption at rest. Moving to your own server later is a backup and a restore.