Try a Few Tutorials
If you're new to blockchain development you can try our tutorials, however if you're just developing smart contracts then any Ethereum based tutorials also apply.
Here's a few great resources to learn about Ethereum
OpenZepplin - has a bunch of great documentation and Smart Contract templates that are battle-tested and contain many of the best practices for Solidity development.
BitDegree - has some good tutorials to follow
Remember that the only change you need to make to run these tutorials on Elastos ETH Sidechain is that you need to change the RPC port to https://rpc.elaeth.io