The Essential Rilke is a lovely edition that has the German and English translation side by side. This really helped me to get at least a basic understanding of the poems, since when the English was particularly dense, I could also check out the sentence in German. Rilke is a very visual poet, using vivid images or adapting well-known myths. I can't say I understood even a third of all that he was doing, but I really enjoyed many of his poems.