10 years ago I started working in the games industry. Along the way I've picked up a few things that I wanted to record (for my own sake!) and to share with you.
Don't be tempted to start designing a solution when the problem is not fully explored and understood, take the time to focus on what you're trying to resolve.
Make sure you understand what the solution needs to accomplish then formalize your findings, write them down. Develop goals.
Present these to other team members, discuss and amend them as required.
It's always better to debate the purpose of a feature than to debate a feature with no obvious purpose.
When a new idea or feature is proposed it's tempting to start immediately identifying flaws or concerns. Avoid writing ideas off or designing fixes based on these assumptions.
Although these concerns are likely valid it's worthwhile giving the people involved time and space to consider and digest what's been proposed.
If the value is there (and time / budgets allows it) prototyping is always desirable. The severity of any concerns will quickly become apparent.
Sometimes a flawed idea can yield gold when you start to really think about it and play with it.
"I don't sell cars; I sell engines. The cars I throw in for free since something has to hold the engines in." - Enzo Ferrari.
Every game has a heart, a core experience, the reason why people play the game.
People will play a game with a great core experience and bad supporting systems, but won't play a game with great supporting systems and a bad core experience. Understanding what parts of your game are vital to the core experience and which parts aren't is a simple concept but much more difficult in practice.
As designers, it's easy to want to thoroughly consider and design every aspect of the game, from a pause menu UX through to player movement. However this has time and budget implications. Depending on what your games heart is, one or both of these may not be important at all.
Enzo Ferrari understood this concept, although Ferraris are known for beautiful aesthetics, the engine is what provides the core experience. "My cars must be beautiful. But more than that, they must not stop out on the circuit. For then people will say, ‘What a pity, it was so pretty'."
Design is a craft. It is skilled work that can be honed.
Keep your design skills sharp, practice them (game jams, personal projects, books, talks etc.) If your job offers self development time use it! Practice outside of work where you can (as a parent I understand this isn't always possible.)
This is particularly important if you're looking to move role, for example from QA to design. Keep your CV, portfolio and any related sites (LinkedIn etc.) up to date as you improve your skills. Show off what you can do.
As a designer the notion that "good design speaks for itself" is appealing but is not true.
In reality how you communicate your ideas is just as important, especially at a conceptual stage where it's likely you don't have any prototype to rely on.
Build a convincing argument for what you are proposing, become a salesperson. Communicate it in a way that's both understandable and appealing.
If proposing an idea or feature via presentation, keep it concise & simple, try and keep it focused. Tell a story, present the issues you are trying to resolve and the goals of your proposal, detail how your idea addresses these issues and achieves your goals, then conclude and answer any outstanding questions.
Of course all of this should always be underpinned by good design!
Where possible' take time to learn about how other disciplines work.
Don't be afraid to have a go yourself (in your spare time). Design doesn't exist in a bubble, it's the culmination of multiple elements.
Understanding the nuances of other disciplines will make you a more efficient designer. Getting a grasp on the work loads & time costs of other disciplines allows you to better gauge what you're asking of them when making requests.
The quality of your feedback is important.
Take time to consider what your are saying and even who you're saying it to. Being rude (or even what the person you are talking to considers as rude) will distract from the point you're trying to make.
However, this must be balanced with being candid and constructive. Strive for a setting where healthy confrontation can take place, where people can talk passionately for or against a proposal or idea.
The more financial risk a project takes on the more commercial viability must be considered.
Although it is possible to over scrutinize commercial viability and at the cost of burn rate (the rate at which you're spending any capital). Trying to find something that's a perfect fit for the current market can lead to paralysis by analysis. I learnt this when taking on personal debt to finance an independent project. I began to over scrutinise the visuals when in hindsight our financial risk meant shipping something would have been better than prolonging development (the project never released!)
The opposite of this is to totally ignore it, and potentially end up spending your whole budget on a game that only you want to play.
Projects have business & financial goals. Understanding those goals and the limitations associated will allow you to focus on what's really important for your game.
Process, pipelines, planning and documentation can often be overlooked or seen as more of a production concern. However it's worthwhile taking care of these, especially in larger teams.
Creating a pipeline that supports taking an idea from concept to production can help avoid;
Allowing time for planning means assets like the vision statement, pillars and values can be focused on and developed to make sure the game has a clear and defined direction.
Design documentation can be used to create design driven QA, where test plans are created directly from design documents and design documents can be updated as QA find new edge cases. This helps avoid design-on-the-fly fixes.
Generally maintaining these helps keep the game moving in a clear direction.
Comparisons between who is the most passionate about game dev or who are devs who make "real" games, AAA devs, indie devs , mobile devs, casual devs, etc. is absurd.
Passion exists everywhere in this industry.
No mater what area of this industry you're in you will always be able to find someone who is passionate about what they do.