This is a hard question to answer because it is pretty dependent on your company's industry, business model, gtm strategy, etc. However, I'll give some examples I've come across in my experience.
1. Website. As a marketer, your website is your storefront - and there are endless ways to continue to improve it to maximize results. Whether your business is built on a self-serve model or you are 100% sales-led - the role of the website is an integral one - spefically in letting prospects and custoemrs know you understand their pain points and have a solution that can help solve them. So - spend some time evaluating your company's website - especially while you have fresh eyes as an outsider, and note ideas for how to optimize. Look at product positioning, audience targeting, clearly articulating value, CTAs, etc. There are likely many quick wins to be found
2. GTM plans. Take a look at how new products and features are currently being brought to market to prospect and existing customers. There are likely quick wins here as well. If there isn't a current GTM template, create one. That is a really great quick win. Make sure your company is taking products to market with the right channels based on what is being released, and to the right audience. Are announcements segmented? (if your company doesnt have clear segments - this should be something on your list of things to help tackle). Are there new and creative ways to get your audiences attention (not everything needs a billboard) -- this can be a clever social media strategy, or in-house videos. When I started at Intercom, the PMM team created 'quick look' videos that were short videos made by an individual PMM, delivered in product. They were not shiny, or overly polished - just a way to connect as humans to customers that didnt require a massive budget or an eloborate project plan. Just a PMM, a script and screen recording software.
3. Sales assets. There are many ways to support a sales team, and hopefully once you've done your listening tour you'll have identified a few areas that are low hanging fruit. I'd say often times an item that shows up on sales wishlists is competitive intel. Not just a feature comparison grid, but how your company can and should win in deals against specific competitors. This is a great first project to take as it often kills a few birds with one stone. on Usually, with some dedicated space and time carved out to do research, this research can be tackled fairly quickly - and as a new person in the company it is a great way to get up to speed on your product and market and build context. You can also start by delivering the content in small digestable pieces. Talking points to SDRs/BDRs, a battlecard for all of sales, a live training, feature deep dives, etc.