Start with the operand
An instruction becomes easier to parse when I first identify which operand is being read and which is being written. A register is immediate state; a memory operand adds an address calculation.
The useful pattern
The common base-plus-index-times-scale form expresses an address without hiding its parts. Naming those parts while reading code makes pointer arithmetic and array access much less mysterious.
For example, a base register can identify the beginning of an array while an index register selects an element. The scale is limited to values supported by the instruction encoding, so the addressing mode is compact but not a general arithmetic expression.
Why it matters
These details show up in bootloaders, kernels, compilers, and optimised programs. Reading the address calculation separately from the instruction's operation makes low-level code less magical and makes mistakes easier to localise.