Ancient astrologers saw your Rising sign as the ship, and the planet that rules it as the one trying to steer that ship. They put a lot of emphasis on the planet steering the ship because of this. It's just as important as your Moon and Sun, and, in fact, it could even be your Moon or Sun if you're Cancer or Leo rising.

Your "Planet Guide" is the planet that is, in essence, guiding your life for that year calling you to engage with the significations of that planet.