A lot goes into making a game, and each game and designer has a different mix of focus and needs for their games. Off the top of my head we have: world building, rules creation, technical and prose writing, art, layout and visual design, feedback and iteration, promotion and marketing, and community support skills. Collaboration and contracting are good ways to make up for weaknesses, but so is practice and patience. So what are you best at? What are you working on improving?

itch.io

I thought I'd share this since it's running for the next month. Both one page RPGs and game jams are a great way to get something creative done quickly. They're especially nice as a breather from larger progress projects.

anydice.com

I'd definitely suggest reading the articles and playing around with the tool a bit. Knowing the likelihood of different dice outcomes has been super helpful for me to do things like tailoring loot tables to include item rarity. I thought it might be useful to others as well.