How do I find information about getting my small flower garden ready for...
Remove the spent foliage from most perennials if that wasn't done last fall. Some of the old vegetation will be easy to remove. Otherwise use shears and cut back to within an inch or two from the ground. This applies to all of the plants you mentioned.
Remove the dead blanket flower stems carefully. These plants have shallow roots, and it's easy to uproot them when trimming. This is OK if the entire top is dead, but look for evidence of new growth at the soil surface. Whether the blanket flower plants appear to be dead or not, expect new ones to grow from seeds nearby.
This is a good time to divide silver mound and hostas if they need it. This can also be done in the fall.
Learn more here: Spring in the Perennial Garden.