Appropriate marketing channels vary distinctly by business type, development level and market positioning. Service vs. product, physical vs. digital, popular vs. specialist, early stage vs. validating vs. growth-phrase vs. stable, desired audience, phase of moon, etc.

In general tooling should be determined by the channel, not the other way around.

The advice given to me by a very successful CFO (many $Ms personal exit, multi-decade angel, now running an accelerator) on my first business was: "test each channel". That means: marketing spend per new prospect, conversion percentage, repeat customer percentage, customer lifetime or fixed-period value estimate, and maybe other channel properties like responsiveness, customer demographic or other data available, markets served, total available inbound volume. Try to keep the building of this data for objective channel-vs-channel analysis as your focus, and don't get distracted. Remember, you're being marketed to. ;)

If you're lucky, you'll find a strong channel. In most cases, you simply need to sink a certain minimum amount of capital to get your customer base large enough to get in the black. Take it from me - not having this war-chest can cost you the business (as it did my first). If you find yourself in that position, workarounds can include partnerships with established networks, acquisitions, pivots to SaaS-conversions ... but again it depends on the business. Good luck out there :)