I decided on this order for myself sometime in my teens, never having been exposed to any kind of instruction re: card games (before or since).

♠ ♦ ♣ ♥

Reasoning:
1. Spades is the most valuable suite, I've always assumed from the fact that it's often the only one in the pack with a fancy ace.
2. Colour alternation just feels right.
3. Diamonds are cooler looking than hearts, also more symmetrical. Also possibly more valuable feeling, if you think of them as big shiny expensive things.