The response could be an entire book, but a few that comes in mind:
do not forget you have to solve a real problem, and that is your goal
use proper tools, ex: if I can solve the problem by using a bash command or a spreadsheet in 5min each month is ok, even if I know few programming languages
KISS, this can be applied in many things, and is one of the hardest to comply. eg: do not over engineer, do not future proof, do not apply micro-performance smart code or "code tricks"
DRY but only until it makes sense, and it doesn't: over complicate things or make unnecessary dependencies (between modules/services)
Single source of truth (applies to Code, Data flow, documentation)
if you had to make a manual action, more then 3 times in a month or so, automate it
keep project-level consistency, even go to extreme enforcing linters warnings as a blocker to PR/merge. If the base is rotten, probably is full of bugs.
leave the code better than you found it, everyday, every task, every sprint
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The response could be an entire book, but a few that comes in mind: