Data & Instinct
Product is a metrics-driven career. Not only do you have to show results, you have to dive into funnels, charts, and other data sources to back up any ideas you have.
This process has always been counter to how I think. I've always been an instinct-driven person. If I sense a problem, I work through it until I understand it inside and out from the customer's perspective. This process of understanding includes manual testing, competitive analysis, and a bit of guest/customer feedback to fill in blanks with insights. The last bit of feedback is necessary for validating the instinct that initially kicked off the process.
For my flow, I usually save the funnel and chart analysis for last. Here's why: if I know there's a problem, then I know what to look for so I can methodically connect the dots. This process helps me frame the problem to my stakeholders and my designers, devs, and fellow product managers. In many ways, I work backward.
This preference doesn't mean that I avoid funnel charts. On the contrary, I love looking at funnel steps and coming up with hypotheses for why there are drop-offs. My problem with funnels is that they are a linear construction of what the PM or business believes the flow is. Some may call this the "happy path." I call it bullshit. Rarely will a customer follow the happy path. Journeys are not linear. To overcome this, I combine breaking down the journey with smaller funnels.
For example: As a guest, I want to purchase a burger with an offer.
I'd break this down into 3 funnels:
Viewing and adding the burger to cart
Adding the offer to their cart
Cart through Payment to Confirmation
(Assuming the offer is not a pre-requisite for adding the burger to the cart)
I'd analyze each funnel and then develop a holistic view of the entire customer journey by stitching all the data together. In some ways, this is a lot more work but I find it gives you greater detail and helps you analyze multiple journeys in one shot as most journeys overlap.
So this was a very high-level view of a how I break down a user journey. There isn't a right or wrong way, so do what's natural and always have someone double check your work. You don't want to report incorrect numbers!