25 Tips for New Developers: Advice from a (Mostly) Self-Taught Software Engineer

Advice for Code Challenges

Read the instructions

Read through the full instructions, take notes if you need to, and read them again before you submit the challenge. Make sure you're doing everything required and you're not missing anything. Show your attention to detail!

Go above and beyond

Even if the challenge doesn't ask you to add tests or styling, or x or y feature, if you have time add those things. They will make your challenge stand out.

Follow best practices

This probably goes without saying, but write clean code that is well documented and follows the best practices for what you're working in. Use a linter, add some comments if needed, and delete or .gitignore unused files.

Advice for on the Job

Keep a knowledge repository

I have a private GitHub repository where I take notes on everything I can. It allows me to create a searchable knowledge base that I can come back to instead of searching over and over again or just purely forgetting. I know a lot of other people also create engineering journals where they write about what they do each day and what they learn, I used to do something similar and I made a cron job on my computer to populate parts of it everyday.

Track your wins

Similar to tracking your knowledge, track your wins. First, if you're having a bout of impostor syndrome, you can come back to them and think of all the awesome things you've done. And you can compare your current wins to your old ones -- you've probably come pretty far.
I keep a document cool things I've done at work, side projects, speaking and writing gigs, positive feedback on my job performance, nice letters from students, screen shots of nice comments on my blog posts, etc.
On the other hand, when you're negotiating at a new job or for an internal raise or promotion, it will come in handy to have a list of the things that make you a great candidate.