Read between the lines. When a playtester asks a question or gives a suggestion, there’s normally something in your game that they felt was lacking.  Take their question or suggestion, but also try and figure out the driving force behind it.
— Scott Almes (@Scott_Almes)
When in doubt, avoid adding complexity to your game. While it’s important to ensure that your game has enough depth and replay value, too much complexity can easily doom a game.
— Darwin Kastle of White Wizard Games
Play as many games as possible. Gaming is a vocabulary with a breadth of history. Knowing how to speak games and what’s already been done and not done, well and not so well will have a big impact on your design and its success.
— Justin Schaffer of Terra Nova Games (@TerraNovaGames)
Immerse yourself in the community! The gaming community is very welcoming, and in my experience designers are always eager to help other designers.
— Suzanne Zinsli (@KabrtZinsli)
It’s important to do bad work. You can iterate on bad work and make it good. You can’t iterate on something you haven’t started.
— Jay Treat (@jtreat3)
Where haste is useful: going from concept to prototype. Where haste is not useful: understanding and applying feedback.
— Ed Marriott (@EdPMarriott)