Harvesting the rose hips: At time of harvest, rose hips should be firm, plump, and have a little give when squeezed. Their color should range from deep orange to bright red. If they are dark red, they are overripe. They are sweetest at this point, but have lost much of their Vitamin C. To harvest, carefully remove 3 cups of rose hips from the stem of the rose plants.
Preparing the tea: Cut off the bloom stem and cut each rose hip in half. If a knife proves to be tricky, try scissors. Scrape out the pith and seeds (I've found this to be easiest with a grapefruit spoon). Rinse the rose hips in cold water and air dry them out on a clean towel or cheese cloth. When dry, mince the hips. Boil in 3 cups of water for 15 minutes. Strain, and enjoy hot or cold.
Other ideas: If you're the creative type, add dried lavender (preferably L. officinalis), fresh or dried ginger, or dried hibiscus flowers to the tea. If the added ingredients are fresh, boil along with the rose hips. If they are dried or flowery, let them steep in the rose hip tea after the boiling phase.