Estimating (points or hours).
Solid Unit Tests for tests that matter. I think "code coverage" becomes an obsession with some devs.
Try to not gold plate everything. Sometimes just get it done.
Don't try and optimise and micro optimise code as you develop from scratch. Get it in a working state, then start optimising.
Dont be afraid to ask, and understand making mistakes is how we learn.
Guinness is all you need on a Friday.
Adding onto 4. As various people said "premature optimisation is the root of all evil" and it's usually better (as you rightly said) to write the working code first then optimise/improve it.
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