Depending on if you have an "old wood" or "new wood" hydrangea, you may need to prune at different times of the year.
Most hydrangeas prefer afternoon shade. But there are some species, like panicle hydrangeas, that do require a bit more sun to grow.
Mulching will help your hydrangeas retain moisture as they grow. There is also cosmetic value, as mulching will help your spring-blooming hydrangeas look well-cared for.