I've been preaching through the Gospel of Mark for nearly seven months now, and I am repeatedly considering questions regarding the appropriate way to read and interpret the narrative. I've been considering this question with particular interest in interpreting the signs (or miracles) of Jesus. The miracle texts are often simply taken as affirmations of Jesus' divine nature, and while that may be involved, I'm not so sure that's what Mark is really getting at with the miracle narratives. So, here's the approach as it stands, and it is, of course, subject to revision.
First, any interpretation of Markan texts must be done in light of Jesus' announcement of the kingdom. When Jesus begins his public ministry, after John's arrest, he begins by announcing the gospel of the approaching kingdom of God and calling all who hear to repentance and belief (1:14). So, the first thing Jesus does is announce the coming kingdom of God. All of his subsequent words and deeds should be understood in light of this initial announcement. Now if we were to stop here, we would find ourselves in the odd predicament of many postmodern expressions of (deviations from?) the Christian faith, and that is of a kingdom not quite sure what to do with the cross. Such an approach leaves us with numerous question marks when Jesus begins predicting and explaining his death (8:32; 9:31; 10:33; 45). "Yeah, we love the kingdom stuff," they say, "but what's with all the brutality at the end." The usual attempt at an answer has something to do with Jesus being the supreme example of God's love, but this is pretty thin without a rigorous substitionary understanding of the cross. So, we must continue.
Second, the kingdom motif in Mark comes to its climax in the crucifixion narrative of chapter 15. Here Jesus is referred to as either "king of the Jews" or "king of Israel" six times (15:2, 9, 12, 18, 26, 32). Further, he wears the garments of a king, a purple robe and a crown, albeit one of thorns (15:17). Thus, in Mark 15, Jesus is either called or adorned as a king eight times in one chapter. This is capped off by the declaration of the centurian that he was the Son of God, a Messianic title, in 15:39. Do we wonder whether Mark is trying to make a point? Jesus has repeatedly hushed people about his identity as the Messiah-King throughout the narrative. Now with the cross comes the full revelation of the meaning of Messiahship. Mark would have his readers understand that the kingdom cannot come until sin has been dealt with, and sins can only be dealt with when the perfect lamb dies as a substitute bearing the transgressions of the many.
So, the bulk of Mark's gospel is bookended with the proclamation of the kingdom and the revelation of the king on the cross. As a result, when we read Mark's gospel, there are at least two questions that should constantly be at the front of our thoughts: (1) how does this text witness to the coming kingdom and (2) how does this text point forward to the cross.
This approach helps us immensely when we come to the miracle texts. Not intending to over generalize particular texts, these narratives become clear evidence of the inbreaking kingdom. When God is king, people are fed, the blind see, demons are cast out. But the signs also point forward to the cross. They point to the uniqueness of Christ to meet human needs, including the all-important need for redemption through his blood.
Another benefit of this approach is that it helps us see the unity of Mark's gospel. Mark does not switch boats in midstream, moving from kingdom in the first half of the gospel to cross in the second half. No, the kingdom is only fully revealed and understood through the cross. A key to reading Mark's gospel is understanding that the two themes are held together and interpret one another. And everything in between should be read in light of this great dual motif of lord and savior, kingdom and cross.
N.B.: I think the observation also helps us understand the so-called Messianic secret. Jesus keeps his identity as Messiah guarded until the end because he knew that an accurate understanding of Messiahship could not be had apart from the cross. Until one encounters Christ's death, one cannot understand his life.