Cloud bills don't get expensive because of bad code. They get expensive because of forgotten defaults — instances that were 'temporary' two years ago, dev environments that nobody turned off, and storage tiers that haven't been reviewed since the account was opened.
The seven steps, in order
1. Tag everything. If you can't attribute a cost to a team or a feature, you can't cut it. 2. Right-size compute. Most production instances run at <20% CPU; the savings from dropping one size are immediate.
3. Reserve what's predictable. Savings plans and committed-use discounts pay for themselves in a quarter. 4. Tier storage. S3 Standard for hot, IA for warm, Glacier for cold. Almost nothing belongs in Standard forever.
5. Kill idle. Old EBS volumes, unattached IPs, forgotten load balancers — they all cost money quietly. 6. Cache egress. Cross-AZ and cross-region transfer is the silent killer. 7. Set a budget alert.