Security effort should follow the threat model, and for most growing companies the realistic threats are credential compromise, unpatched software, and misconfigured cloud storage — not targeted zero-day exploitation.
Multi-factor authentication on every account that touches production or company data is the single highest-value control. Prefer hardware keys or authenticator apps over SMS, which is vulnerable to interception and SIM-swap attacks.
Least privilege is easy to state and hard to maintain. Access tends to accumulate: people join projects, gain permissions, and never lose them. A quarterly access review that actually removes stale permissions is worth more than an elaborate policy nobody enforces.
Dependency management is where modern applications are most exposed. Automated vulnerability scanning in CI, a defined process for triaging findings, and a habit of keeping dependencies current beat an annual manual audit.
Secrets should never live in source control or environment files committed to a repository. Use a managed secrets service, rotate credentials on a schedule, and make rotation painless enough that it actually happens.
Logging and alerting turn an invisible incident into a detected one. Capture authentication events, privileged actions, and data access. Alert on the patterns that matter — impossible travel, privilege escalation, bulk data export — rather than everything.
Backups are a security control, not just an availability one. Ransomware resilience depends on backups that are isolated from production credentials and, critically, on restore procedures that have been tested. An untested backup is a hypothesis.
Finally, write an incident response plan while calm. Who is called, who decides to take a system offline, who communicates externally. The plan matters less than the fact that these decisions were made before the pressure arrived.