I think Tim Keller gives the best summary of what our approach should be:
Comments and thoughts about Jesus in the Old Testament:
Don’t get to Christ artificially. This is a big subject of course, but I believe two of the best ways are (a) by identifying in your text one of the many inner-canonical themes that all climax in Christ (Don Carson’s language), and (b) identifying in your text some “Fallen Condition Focus,” some lack in humanity that only Christ can fill (Bryan Chapell’s language).(Via the Resurgence blog.)
Comments and thoughts about Jesus in the Old Testament: