What is the biggest lesson you've learned marketing for a startup?

This could be your own or working under someone else's startup 😊 Mine is probably working on SEO early on when you're first working on your startup. SEO takes time to get going, and if your website is completely new, you can't expect results straight away. Also, you don't need 'paid' tools to get going. I did my initial research with a free trial with SEMrush and then subsidized my results over time with Ubersuggest.