In general, you can substitute one teaspoon of dried herbs for one tablespoon of fresh herbs and vice-versa (which is a one-to-three ratio, by the way). But let taste be your guide. Packaged dried herbs start out with a stronger taste than fresh herbs, but lose their pungency as they age. So if you’ve recently purchased the container, you might want to use a light hand, or add a bit more if the herb is older. When possible, use fresh ingredients to gain the most flavor.
If you’re grinding your own spices instead of using pre-ground, you might use a bit less than the recipe calls for, as fresh-ground spices are more flavorful than pre-ground.