Method signature — Prefer using objects over primitives, especially when argument ordering is important and unclear with primitives.

Static factory methods — Use static factory methods to create objects. These can return interfaces with hidden implementations.

Fluent API — Consider fluent APIs as alternatives to complex constructors for better readability.

Weakest possible types — Accept the weakest possible type to allow flexibility in usage.

Avoid checked exceptions — They leak implementation details and increase coupling. Favor unchecked exceptions or functional handling.

Prefer small interfaces — Split large interfaces into smaller, more focused ones.

No booleans in method signatures — Avoid methods like save(true), which are unclear. Use enums or split into separate methods.

Return empty collections / booleans — Never return null — return empty collections or Optional/boolean instead.

Use meaningful return types — Avoid returning raw data types when domain-specific types convey more meaning.

Defend API contracts — Return unmodifiable collections to prevent external mutation.