I don't have a set framework as such, but this is the approach I'd take:
- Meet with stakeholders across the business to understand what's working, where the gaps are that PMM might be able to fill, and ask what they think is the highest priority. Ask lots of questions to understand what the underlying need/problem is, as the 'solution' people ask for might not always be the best way to solve the problem or might be better solved by another team. This is also a great opportunity to start educating others on what PMM does and how they should expect to work with you, if it's a new function. Identifying some small 'quick wins' can help establish your credibility and build relationships with those stakeholders.
- Understand the business strategy and goals. This will help you know what you're working towards, and then you can prioritise needs based on whether they will help towards those goals.
- Get to know your customers and your market. As well as understanding the pain points internally, it's also helpful to understand your current position in the market, how your product is perceived, how you stack up against competitors, what your customers say about you and so on. This should help you identify the highest priority areas - especially where these align with internal needs (for example, if your sales team is complaining you are losing deals to a specific competitor, and then you also find that the market doesn't know how you're differentiated, that may be a sign that you need to strengthen your messaging and enablement against that competitor)
- Think about what you want you and your team to be focused on. It's easy for PMM to end up as a 'catch all' and end up doing a ton of things that aren't really product marketing, especially if the marketing team overall is small. That might be what the business needs at that time, and that's ok, but knowing where you want to get to will help you advocate for more resources and moving that work out of the team in the longer term.