The structure of Tolstoy's Anna Karenina has two focal points: Anna's story and Levin's story. According to Sydney Schultze, in The Structure of Anna Karenina (Ardis 1982), for the most part, these stories alternate by groupings of chapters which can be referred to as "segments." These segments are in turn grouped into the "Parts" which form the overall structure of the novel.  Schultze shows that of the total 239 chapters, 113 chapters grouped into 17 segments belong to Anna, and 126 chapters grouped into 18 segments belong to Levin. If you want to follow each story, based on your interest, here is Schultze's schematic:

Part I: Anna 1-4, Levin 5-15, A 16-23, L 24-27, A 28-34
Part II: L 1-3, A 4-11, L 12-17, A 18-29, L 30-35
Part III: L 1-12, A 13-23, L 24-32
Part IV: A 1-6, L 7, A 8, L 9, A 10, L 11, A 12, L 13-16, A 17-23
Part V: L 1-6, A 7-13, L 14-20, A 21-23
Part VI: L 1-16, A 17-25, L 26-30, A 31-32
Part VII: L 1-11, A 12, L 13-16, A 17-31
Part VIII: L 1-19

We'll discuss Anna over two classes, Parts I-IV, then Parts V-VIII. I suggest, that you emphasize these selections:

Part I: A 1-4, L 5-15, A 16-23
Part II: A 4-11
Part III: A 13-23
Part IV: A 12, L 13-16, A 17-23
Part V: L 14-20
Part VI: A 17-25
Part VII: L 13-16, A 17-31
Part VIII: L 1-19