Here’s a detailed roadmap to get into Cairo smart-contract development, done by Omar Espejel (@espejelomar)
Starknet Development: A Coder’s Map
Four key steps. Essential readings, exercises and resources. Start here: 
-
Starknet Book
Chapter 0: Introduction - The Starknet Book
Chapter 1: Getting Started - The Starknet Book -
Cairo Book
Chapter 1: https://book.cairo-lang.org/ch01-00-getting-started.html
Chapter 2: https://book.cairo-lang.org/ch02-00-common-programming-concepts.html
Chapter 3: https://book.cairo-lang.org/ch03-00-common-collections.html
Chapter 4: https://book.cairo-lang.org/ch04-00-understanding-ownership.html
Chapter 5: https://book.cairo-lang.org/ch05-00-using-structs-to-structure-related-data.html
Chapter 6: https://book.cairo-lang.org/ch06-00-enums-and-pattern-matching.html
Chapter 7: https://book.cairo-lang.org/ch07-00-managing-cairo-projects-with-packages-crates-and-modules.html -
Practical exercises
Starklings: https://github.com/shramee/starklings-cairo1
@nodeguardians: Thinking Cairo: https://nodeguardians.io/dev-hub?s=devhub-campaigns&sc=cairo-thinking
Starknet by Example by @NethermindEth, @NethermindStark, https://starknet-by-example.voyager.online/ -
Back to the Starknet Book
Chapter 2: https://book.starknet.io/ch02-00-starknet-tooling.html
Chapter 3: https://book.starknet.io/ch03-00-architecture.html
Chapter 4: https://book.starknet.io/ch04-00-account-abstraction.html
Always reference Cairo [https://docs.cairo-lang.org] and Starknet [https://docs.starknet.io/documentation/] docs.
Now, build the future, be it a universe or “just” a cool game ! 
