Target about 5% week on week growth. If you have $1000 in sales this week, you'll want $1050 in sales next week, $1200 weekly sales in a month, , $12,600 weekly in a year.
This is actually a very conservative growth chart. Personally if I couldn't get 7% week on week growth, I'd worry about my business model.
If you can just hit this, you'll be fine.
If you don't, this is where all the startup frameworks kick in. You can set up a Business Model Canvas, look at whether your assumptions are correct. Attack either the low hanging fruit or the riskiest assumption. If you can fix the highest risk items, you can usually start generating good growth without any paid marketing.
Normally the problem is that the business hasn't hit product-market fit. Either the product isn't good enough, or it hasn't been able to expand or pitch itself into the market. When you hit product market fit, you'll be dealing with some crazy growth and struggle to keep up.