*Kind of a broad question but in case the powers that be decide to keep it ...*

Vintage simply means that you are denoting an identifiable period of time. Whatever you can do to invoke your chosen time period is fair game. It's a gestalt impression, not one particular piece of the puzzle.

**The easiest ways to draw on an era is to analyze the techniques, motifs, palettes, typography, and subjects used at that time (but choice or limitation).** In your example, the combination of jewel tone blue with bright red or the avocado green are period colors. The typography, on the other hand, lacks the hand-brushed technique to back up some of the implied vintage. Sometimes compromise is necessary to hit the deadline ;)