A list of useful resources and accompanying descriptions, with especially pertinent ones marked.
FTC Discord
The unofficial FTC Discord server is a discussion-based community server that has teams ranging from first-year rookies to Winning Alliance Captains at the World Championships. It also has a channel for direct access to vendors.
Being a Team
Covers how to start, organize, and run an effective team.
A list of general tips for your team’s design process.
Design Tradeoffs
Goes over some common robot design decisions and typically superior alternatives to them.
Drivetrains
Because it doesn’t matter how good the rest of your mechanisms are if the robot cannot get to where it needs to be (except maybe if you’re 8813 in Relic Recovery).
Active Intake
Because you want to be able to pick stuff up. Touch it, own it.
Linear Motion Guide
Moving things further than the constraints of the robot is an extremely common task, and linear motion is often one of the best ways to do this.
Power Transmission
Different ways to get rotation from point A to point B.