I love companies that get their start on Reddit. While I'm not familiar with yours specifically, generally speaking you are having a dialogue with your target audience. This is critical for validating product-market fit and learning about who your target audience is and what they care about. I mean, people will literally tell you if you ask them.
Beyond that, if you are able to harness the goodwill of the hive mind, you can reach that critical front page trajectory pretty quickly. If you are one of the few brands that lucks out in dominating in a given subreddit for a period of time (not through advertising), that's a huge validator. Further, pleasing that audience can result in lots of earned social activity which is great for a nascent brand.
For FB specifically, Lookalike targeting is very powerful, and banner blindness is a very real thing that requires constantly refreshed creative depending on your reach (excluded audiences can be important here to avoid wasting impressions). Unless you are using a FB PMD (basically a tool to manage FB that offers loads more than the basic Power Editor), splitting stuff out for granular targeting can be a PITA. Break out your audiences in meaningful chunks where you can gain insight and better improve your creative. More importantly, make sure the rest of your analytics are in order so you can understand what people exposed to you through FB are doing on your site. For a brand that may not be well-known yet, you might avoid a lot of bigger attribution issues with conversion tracking, but make sure you think carefully about whether you want view-through attribution settings enabled for conversion tracking. They are by default, and that can skew things and they may not be worth as much as you think they are based on the stats.
In terms of hiring for marketing, most strong marketers know there's a lot outside their control. There's definitely a difference between marketing a sales. As such, I would actually avoid focusing too heavily on commission as that can be a turnoff that says you aren't putting your money where your product is so to speak. That said, if the person has significant control over the full funnel and relevant touch-points (a requirement to be successful when it comes to online marketing), they might be willing.
The other side of that is the affiliate world. These are essentially 100% commission marketers. You can get mixed results, but it manages your direct financial risk a bit better than hiring someone internally in some cases. There are real benefits to having an internal hire though that you simply won't get with affiliates as they are by definition mercenaries.
Like many professions, comp can be relatively simple. A competitive base plus a well-detailed bonus structure, solid benefits, potentially equity if appropriate, and a great culture coupled with a product with lots growth potential are all things that can land a solid marketing hire.