What are some of the best resources for Product Marketers to refer to as they grow in their careers?

Sharebird is a fantastic network. It’s wonderful to see communities sprout around this fun and challenging career path that can lead to a variety of successful positions. Use your network and ask questions as much as possible.

Today, there are so many fantastic resources and community groups, certainly more than when I started as a pmm. So I'll focus my answer on other ways you can continue to grow professionally:

• Find a mentor. Identify a product marketer who's further on in their career than you and ask them to be your mentor. It doesn't have to be someone you know or have worked with in the past. Reach out and explain what you are trying to accomplish and what pmm skills you are looking to develop. Ideally, you want to find someone who works in your industry and has a career path similar to the one you're pursuing. Once you have a mentor, do the hard work and come prepared with topics, scenarios, and situations that you need guidance on. Your time with your mentor is the best opportunity to grow your PMM skill set and leadership skills, especially if you want to become a manager.
• Become a mentor. I'm a firm believer that everyone has something to give, and that mentoring is as fulfilling to the mentor as it is for the mentee. Identify your PMM superpowers and offer younger product marketers the opportunity to learn from you. I guarantee you'll learn a ton from it, too - including how things are done in other companies, how to handle new situations you might not have dealt with before, how to provide meaningful coaching. You might be saying, "I'm still learning myself. What do I have to offer?" so I encourage you to dig deep and find what it is that you do well. I'm sure there are a few things you can think of. 
• Follow PMM stars on LinkedIn. In addition to all the slack channels, webinars, and AMAs, pay attention to what is organically shared by other PMMs. IMO, these are the real gems - daily experiences, POVs, best practices, and templates that are super impactful and you can quickly put into practice in your organization. (Btw, these are the folks you can later target as your potential mentors).

First of all, you are in the right place in the Sharebird Community :) I would also recommend the Product Marketing Community and PMA. There are not only resources you can consume, but also communities you can consult, stay active with that can enrich your professional and personal life with meaningful connections, and also provide you with additional professional growth opportunities.

Great question! I'd recommend 4 things:

1. Stay up on current trends in the industry. This seems like a no-brainer, but it's one of the things that I see folks deprioritize as they're working to get things done early in their careers. Whether it's AdWeek, Forbes, you name it! Stay up on the recent trends and technologies on a weekly basis. 
2. If your organization has a sales team, get to know them and your customers. They're your primary "customers", so spend time listening - understanding their challenges, the opportunities they have, and identifying valuable ways to help them.  
3. Mentorship matters! If you don't have a mentor, reach out to the senior leaders and individuals within your company that you admire, so you can learn from them
4. I highly recommend programs like The Marketing Academy, which are cohort-based and meant to help support both your personal and professional growth.

Best of luck to you!

Sharebird is an absolutely wonderful network to join and become a part of. It's wonderful to see communities like this grow and foster collaboration across folks looking to grow in their careers. The contributions and content coming from these communities is a great way to hear from leaders and peers facing the same types of challenges and provide a wealth of knowledge as you navigate your own career.