Honestly, if you can drive real signups from a community like Reddit without sounding like a shill, you're already ahead of most "growth" people I've worked with. That's a skill you can monetise straight away.
I'd frame it as "organic user acquisition" or "community-led growth" - founders get twitchy when they hear "Reddit marketing" because they picture burned accounts and fake engagement. Been there. Seen the damage.
Start with indie founders or B2B SaaS types. Offer a flat monthly retainer or campaign-based pricing until you understand which angles are repeatable. For example, one colleague scaled a dev tool to 2k signups in 6 weeks just by posting tactical walkthroughs in relevant subs - no links, just value. That's the kind of case study you need to build.
Charge based on output (tested campaigns, community assets) rather than promises. Then once you've got 2-3 proven plays, triple your rate. Most people can't do this without getting banned. If you can, that's your moat 👍