How to get started?
3Q2022 - initial version
Disclaimer: I'll try to keep it short.
It should be noted that obviously there is no fundamental Web3 (or Blockchain/Crypto/DeFi etc) education yet. Basically all of the practitioners and project founders obtained knowledge through experience and own research.
There is a number of educational courses (almost every major exchange has some learning materials, a good example: https://academy.binance.com/en), but given the fast-changing nature and constant broadening of the scope of Web3, they either have to be rather general, or quickly become obsolete [Upd Feb 2025: as this guide has already become].
The basics of blockchain technology and some of the main applications stay the same, though.
Given all that, the basic approach to learn (and subsequently become more proficient) is as follows.
Start with the blockchain basics - understand main principles and terms used.
Continue with more detailed research of separate applications of blockchain technology, e.g. (this is not a comprehensive list of applications, but just some of the most widely-used ones):
Digital Money (Bitcoin history and basics)
Ethereum and Decentralized Applications (dApps)
Non-Fungible Tokens (NFT) and Soul-Bound Tokens (SBT)
Decentralized Autonomous Organizations (DAOs)
Metaverses and GameFi (Gaming + DeFi)
Decentralized Finance (DeFi)
The approach here is simple: while reading an article on a specific topic, highlight any new terms and research them separately. This way you will gradually form a comprehensive (though rather general) understanding of the whole ecosystem.