Here is a growing collection of tips, tricks, and techniques for the Arduino.
TA0297 Quick Guide, PDF, Arduino
The Arduino Uno & Elements: The Arduino Uno Is Open Source (Meaning Its Designs May Be Freely Copied), PDF, Arduino
How to use Wokwi Arduino Simulator in 2022? What is Wokwi?
The GeekDad Arduino Guide: Getting Blinky With It
Troubleshooting Guide for Arduino - GadgetMates
How do I Power my Arduino? - Robocraze
Mastering Photoresistor Sensors With Arduino Uno: Tips, Tricks, And Projects
Arduino Interrupts : 5 Steps - Instructables
Arduino Timers [Ultimate Guide]
Tips and Tricks for Programming Arduino