These are pieces of knowledge I got from several people and from my own experience.

back to the beginning

If you want to learn more about a technology (or concept, etc), try to learn from who created it.

This is nice because you can see more about why things are the way they are.

Try not only learn from people who teach about it but not actually understand it deeply.

over engineering

I can't tell how many times I saw myself and others worrying too much about scaling the app too early resulting in over engineered projects.

I try to always keep in mind to do the simplest thing first (with good sense) and only scale when needed.