I'd agree with lots of the other points here about following your Gut and finding a mentor.
One thing I'd add is to make sure to listen. You'll be a part of a small, dynamic team who are embedded deep in the details of the problem you're trying to solve every day. Your peers, your CEO and your own intuition will be giving you certain types of feedback - it's how all companies are - but those are not the most important places to go to find answers when you're designing a product.
Make sure to break out of your comfort zone whenever you can to meet with and listen to the people who are trying out and using your work. Put yourself out there, don't just design from behind your desk. Understanding and empathising with the user point of view, their tools, their thoughts and frustrations will guide your work better than any internal team processes or workflows ever will.
I'd agree with lots of the other points here about following your Gut and finding a mentor.
One thing I'd add is to make sure to listen. You'll be a part of a small, dynamic team who are embedded deep in the details of the problem you're trying to solve every day. Your peers, your CEO and your own intuition will be giving you certain types of feedback - it's how all companies are - but those are not the most important places to go to find answers when you're designing a product.
Make sure to break out of your comfort zone whenever you can to meet with and listen to the people who are trying out and using your work. Put yourself out there, don't just design from behind your desk. Understanding and empathising with the user point of view, their tools, their thoughts and frustrations will guide your work better than any internal team processes or workflows ever will.