Almost 4 years in software engineering and that's what I have learned.

1. The cost of time and engineering is more higher than that of servers.
2. Developer productivity and a technology's ecosystem are more valuable than a runtime's efficiency or the raw speed of a programming language.
3. Programming languages that are often considered slow and criticized for technical deficiencies or poor design are usually the most used and favored for building real-world software, from small to large scale, due to the flexibility they provide to engineers.
4. The choice of a tech stack, often said to depend on project requirements, is misleading and untrue; in reality, it depends on the expertise of the senior engineer and team.
5. Real agile teams don’t follow agile practices rigidly; instead, they develop their processes to maintain agility.
6. Best practices are often biased.
7. Healthy communication is key to a team’s success.
8. GitHub is the best tool for tracking and managing software development.
9. The first priority is to make it work.
10. Mastery of the basics makes you advanced.