To get the big picture right, pick up a good book on strategy. I highly recommend reading Good strategy bad strategy. It might not seem applicable to marketing directly but it will help you put together a strategic framework you can use to solve any problem and how to think strategically. Once you have done that, put together all the high level questions you need to figure out in a doc: What problem are we solving? Who are we selling to? Are they looking for something like this or do we need to educate them about this product? What triggers/events lead them to look for something like this? Why are they buying from us? Where do they go when they are looking to buy something like this? Once you have put these larger questions down, your day to day will help you figure these questions out and the more clarity you have on them, the more you will be able to focus on doing the right things instead of just doing a lot of things marketing blogs might ask you to do.

Talk to some customers who bought recently from you. Why did they start looking for whatever product you were offering? How did they go about looking for options? Who else was involved in the decision (even the smallest suggestion from a friend here counts)? Why did they choose you? Pay very close attention to the words they use, especially the emotionally loaded words (strange/obvious/insane) an ask them to unpack it for you. And finally ask them - how would they describe your product to a friend? That should give you a clear understanding to why people buy your products, the conversation going on in their heads and the language they use to describe your product which I think should give you all the material you need to create your campaigns.

If I had to rephrase your question, you are trying to understand what part of the website were people able to understand, which parts were they not. Sure, analytics, heatmaps etc will help you a lot with it but nothing is better than actually talking to some people. This could be over chat where you could ask people if they understood what the service was about but is best done over call - I don't know your business to tell you how to get people on call but nothing beats the density and richness of information and surrounding context you can get when you get users on a call.