You want your acquisition efforts to be profitable because without profitability you’ll find it really hard to scale things up (unless you’re a VC-backed business).
Basically, what you try to do with "growth marketing" is that you start wiring in your other growth systems, and simultaneously run aggressive A/B-tests to fine-tune all aspects of your acquisition strategy.
By creating a more automated acquisition effort, with marketing automation, well-operated funnels, and rapid testing – you'll be able to afford higher customer acquisition costs.
You want your product and your "loops" to do some of the heavy liftings...
You want to retain customers and users to drive higher lifetime value.
In general, you want to plug the big holes in your funnel before you drive a lot of traffic because otherwise much of that traffic—which is expensive to get—will be wasted.
This takes time - but the much clichée advice of "doing things that don't scale" really come in handy here.
When you can run systemized manual acquisition efforts, then you can map it out and start automating the steps that you take. Start with templates, then outsource it, and lastly automate it.