Drying your spruce tips is very easy. If you have a dehydrator, that should work perfectly. If you don't, you can just spread the tips on a parchment-lined baking sheet and place them in the oven at around 100 °F until completely dry. Keep the oven door cracked so the moisture can escape. 6 hours should usually do it, but your mileage may vary according to your local climate and the size of your spruce tips.