A. Private subnets should ideally have individual route tables to control the flow of traffic within and outside of VCN.

B. Ensure not all IP addresses are allocated at once within a VCN or subnet; instead reserve some IP addresses for future use.

C. Use OCI tags to tag VCN resources so that all resources follow organizational tagging/naming conventions.

D. For resources without public IP addresses that need to initiate connections to the internet you can use an Internet gateway.