Scoring is what incentivises different behaviours. So, to a large extent, your scoring system IS your game. A good scoring system can provide a higher skill ceiling, differentiation of skill, reward interesting/fun play, tension of risk/reward, and real meaningful choices.
— Bez
Most strategic games are about decisions, and when you decide to do something you’re also often deciding not to do something else. And there is a cost there, and that cost is often not appreciated by some designers.
— Tom Lehmann
Your game is 3 to 10 times harder than you think it is.
— Elizabeth Hargrave
To make a bridge to the familiar, hobby gamers have to realize what is familiar to a casual gamer.

Worker placement? nope
Variable turn order? nope
Variable set-up? not really
Deck construction? nope
Game phases? nope

You can ask a casual player to learn 2-3 new things at most
— Dominic Crapuchettes
A key facet of modern design is that players are engaged in the game from start to finish. Make losing as engaging as possible.
— T.C. Petty III