It might seem like a small thing, but you'll want to ensure that the decorative objects you pick are well-made so they don't fall apart, unravel, or start to look bad (after all, that would defeat the entire point!).
Look for objects with good reviews, from reputable sellers, and ones appropriately priced. It can be tempting to source lots of decorative objects at low prices, but the resulting tableau may not measure up to your ideals. Go slowly, and pick up decor piece by piece, thoughtfully, at investments which make sense to you.