If you're not a founder, NEVER take equity in leu of salary. If they offer a competitive salary and equity, that's a significant plus, but equity as a portion of your compensation value is essentially a scam. if the company goes under or you're let go before the cliff (which is usually two years or more, a lifetime in this industry), all that money disappears: not true of salary. If a founder or officer alludes to houses, cars or other riches as a pitch to join their company run. Seriously.
Take the time to understand systems and infrastructure. Not every dev needs to be a kubernetes expert, but the big difference between a code monkey and a code assassin is that the assassin can deploy their own code to production if necessary. If you're a web dev and you can't configure nginx or apache, you have a gaping hole in your skillset.
Launching off the last point: learn to be competent with linux. Linux is the preeminent environment of the software world and it pays huge career dividends to be able to script, configure, compile, install and maintain linux software and systems.
RTFM. This is a big one. Don't skim. Relax and dedicate some time to a thorough understanding of details. You can save yourself an immense amount of time when working with a new library/framework/language if you actually read the manuals and understand what your tools are capable of, otherwise, you end up wasting tons of time brute forcing your way into a crude solution that may have been trivially and correctly solved by utilizing the tool's strengths and features where appropriate.