How are the views of Hume and Schopenhauer similar?

They are different in the sense that Schopanhauer largely accepts Kant's metaphysical worldview (i.e phenomenon and noumenon, our brains cognizing raw material into the objective forms of intuition: space and time). David Hume was an empiricist and a skeptic who saw impressions as usually leading to corresponding ideas. For Hume, there were different ways to describe relations of ideas and ultimately things like mathematics and logic were just large systems of related ideas. Schopenhauer and Hume did not have room for God in their respective metaphysical schemes. The result was that humans should just make the best of things. Hume did not write explicitly about this, but despite being a skeptic, he was regard by his contemporaries as very cheerful. Schopenhauer, however, held that our will is constantly dissatisfied. As a result we are constantly seeking new pleasure, but rarely finding it or feeling the effects of loosing it. For Schopenhauer, only the life of an aesthetic or a sage could provide some sort of escape from our ultimately difficult existence. By contemplating art and music and denying ourselves we could distract ourselves from the pain of existence.

Summary:

They disagrees on metaphysics [in some sense Hume rejected metaphysics (open to interpretation)]. However their philosophies of what to do in everyday life was largely similiar.

Just remember this is just my interpretation. Stanford Encylopedia of Philosophy is good and online.