Is there a documented migration strategy to move apps, APIs, tables from one instance to another?

[Snehal13]

Is there a documented migration strategy from one instance to another? like best practices, process and checklist to ensure minimal breakdown and issues are migrated instance.

Cannot clone as only specific artifacts are to be migrated (apps, APIs, tables, scripts, pages, widgets and not everything)

[Bert_c1]

Which instance has the desired artifacts to be added to another instance? If development changes then I expect they are on dev instance. If so, you can use Update Sets to promote to higher instances. (Moving Applications is also supported.) Going from production to lower instances is what Cloning is for. So those instances better match what is in production for new development. But retain some instance specific configuration as the others here indicated.