Perhaps the part I agreed with the most is "don't hire too fast". It's difficult for me to think of a startup (or, honestly, any company) that failed or experienced pains from hiring too slow, but I can think of tons of problems (often from personal experience) from hiring too fast.
One piece I couldn't help roll my eyes at is the "don't use Jira" bit - like the sun rising in the East, bashing on Jira is the favorite past time of engineers. Depending on your type of startup, Jira may be a great tool for the job. E.g. if your company has lots of different workflows it needs to support, it can be very easy to waste a ton of time due to "dropped balls" if things aren't tracked well and issue ownership isn't explicitly clear. Of course, it's easy to waste a ton of time over-complicating Jira with a million unnecessary issue states, but IMO Jira has made it much easier for small teams to use it and be productive quickly (i.e. team-based projects). I'm also not saying Jira is the best tool to start with (my last startup stated with Trello and it worked well), but once you get into production and have a lot of operational issues to manage and prioritize alongside new feature development, you're likely going to need some Jira-like tool to keep everyone aligned and informed.