[professoretc]

Prefixes come first, 1 byte each, order doesn't matter except that REX, if present, must come last. Then the opcode, 1-3 bytes. Followed by Mod R/M byte, if present. Followed by SIB byte, if present. Followed by address/immediate, 1, 2, 4, or 8 bytes, if present.

Ugh; there's a reason why I'm switching my architecture course to MIPS32.

[WalterBright]

One day I realized I could just look at a hex dump and see some (not all) of the instructions in my head.