#4 - You will, eventually, need to learn some back-end code.<p>November of last year, I began re-designing my site to use AngularJS / Firebase. After looking at some examples, I fell in love with the live updating of the data, single page design.<p>In July it went live.<p>And now, on the edge of October, I find myself writing pieces in PHP / MySQL and accessing them via a http request to do any number of things from querying user data, to sending email via Mailgun, to triggering a Twillio message.<p>Pick a language / database - doesn't matter if its PHP or Ruby, MySQL or Postgres - but learn 1 of each - I still love and use Firebase, but it's no good if I can't perform the simplest of queries like "select * from users where school_id=x". No fancyness on the frontend will negate the power of a properly formatted sql statement.