Most growth hacks are BS. Here are 3 free ones that actually moved the needle for us

After wasting $5k on shady 'growth experts,' we focused on scrappy, free tactics. These delivered real results:

1. Reddit AMAs: Hosted a casual 'Ask Me Anything' in niche subs (not promotional!). Gained 200 email subs from genuinely helping people.
2. Tool repurposing: Used Google Alerts to find forum threads asking about problems our product solved. Responded helpfully (no links unless asked).
3. UGC mining: Ran a contest for customer photos/videos, then reused them in ads (with permission). Cut our CAC by 40%.

We compiled a free case study with screenshots of our analytics. What underrated tactics have you tried?