Smart contract development is a crucial aspect of blockchain technology, and writing secure, efficient, and scalable smart contracts requires expertise in programming languages such as:

1. _Solidity_ (for Ethereum and EVM-compatible blockchains)

2. _Rust_ (for Solana, Polkadot, and other blockchain platforms)

3. _Go_ (for Hyperledger Fabric and other blockchain platforms)

4. _JavaScript_ (for blockchain platforms like EOS and Corda)

5. _Vyper_ (for Ethereum and EVM-compatible blockchains)

Smart contract developers need to consider the following key factors:

1. _Security_: Writing secure code to prevent vulnerabilities and protect against attacks.

2. _Efficiency_: Optimizing code for gas efficiency and reducing transaction costs.

3. _Scalability_: Developing contracts that can handle high volumes of transactions and users.

4. _Auditability_: Ensuring contracts are transparent, traceable, and compliant with regulations.

5. _Upgradeability_: Designing contracts that can be easily modified or updated.

Some best practices for smart contract development include:

1. _Code review_ and _testing_

2. _Using established frameworks and libraries_

3. _Following security guidelines and standards_

4. _Documenting code and functionality_

5. _Continuously monitoring and updating contracts_

By following these best practices and staying up-to-date with the latest programming languages and blockchain technologies, developers can create robust, reliable, and efficient smart contracts that power the decentralized applications of the future.