When figuring out the aspects, it is the closest distance between two planets, and that can take you clockwise or counter-clockwise. Suppose your sun was at 15-degrees Aries, and your Jupiter was at 15-degrees Pisces. You'd calculate the aspect from Aries to Pisces (30-degrees), instead of 330 degrees going the other direction. That's an extreme example, but it will help you understand why you always use the shortest distance to calculate aspects.

If I haven't been clear, let me know, and I'll post a graphic (one picture worth a thousand words...they say).