I have been a junior QA engineer long enough to have made most of the classic first-year mistakes, and recently enough to remember exactly how confusing the first months felt. If you are starting your first QA job, this is what I would tell you. Not the polished version, the one I actually lived.
Learn the product before the tools
My instinct in week one was to install everything: automation frameworks, API clients, emulators. Most of it was productive-feeling procrastination. The testers my team trusted were not the ones with the best tooling; they were the ones who knew how the product behaved in weird states. So I spent my first weeks using the app the way real users do, breaking flows on purpose, and reading old JIRA tickets. Old bug reports are an underrated map of exactly where a product is fragile, and they are sitting there waiting for you.
Ask reproduction-quality questions
There is a difference between "login is broken" and "login with a valid account fails on Android after backgrounding the app on the OTP screen; steps and video attached." I learned to ask questions the same way I would file a bug: what I tried, what I expected, what actually happened. Developers answer those fast. Vague questions get vague answers, and as the new person, you earn the right to interrupt busy people by making your interruptions cheap to handle.
A junior QA engineer's bug reports are their reputation
For a junior QA engineer, trust arrives one ticket at a time. Every report I file has numbered steps, actual versus expected results, environment details, and evidence, usually a screen recording or logs. When a developer can reproduce your bug in two minutes, they start taking your tickets seriously. Every "cannot reproduce" bounce costs you a little credibility, so I treat "cannot reproduce" as my bug to fix before I reassign it.
Automate later than you think, but not never
I wrote no automation in my first month, and I am glad. You cannot automate a product you do not understand; you just encode your ignorance into scripts that fail for the wrong reasons. Around the time I could predict where regressions would appear, I started small, with smoke flows. Eventually I built our mobile automation workspace in Maestro from zero and wired the smoke and regression suites into GitHub Actions, which cut our regression testing time roughly in half. That project only worked because months of manual testing had taught me exactly which flows deserved automating first.
Find the thing only you cover
My niche partly found me. I am a native Arabic speaker on a team that ships RTL builds, so I became the person who catches mirrored layouts, truncated Arabic strings, and bidirectional text bugs, and then the mobile automation person on top of that. Your niche will look different: API testing, test data, accessibility, performance. Pay attention to what your team quietly lacks, and become good at it before anyone asks you to.
What I would do differently
Honestly? I stayed quiet too long in refinement and planning meetings, assuming my questions were too basic to ask out loud. Almost every time I finally asked one, it turned out a developer had the same doubt. Questions asked in refinement are the cheapest bugs you will ever find, because nobody has built anything yet. I also spent too much energy trying to look busy and not enough writing down what I was learning; the notes I did keep became the backbone of my regression checklist later.