Agree with looking at tools like SEMrush, Spyfu, and Alexa to find out what your competitors are doing. That will not only help you understand what they're doing, but also show you opportunities that may be undervalued, and areas you should ignore for now since they are so competitive.

But you should also be looking at how you will measure ROI, not just spend. Measuring spend is ridiculously easy, be sure you have a digital sales funnel set up for every ad you do so you can properly track ROI. You should be able to show 3x return for every dollar spent.