Learn how to use libraries

I’ve been coding for about 25 years and back when I got out of college I use to say "I don’t use 3rd libraries because I like to know what every part of the program is doing". To me, a library was a black box that prevented a program from being actually understood in its entirety. What I didn’t realize is that know how and when to use (or not use) libraries in order to be an effective dev is perhaps just as important as being able to write code yourself.