There might be a small guide included with the artbook, but we don't really do separate walkthroughs/guides anymore since we do tend to update our games post-release, sometimes with new choices/content, and no players have written any so far. That said, if you make use of the in-game affection tracker, you can rollback from choices that don't give you any affection. For the good ending, you want the tracker to be almost completely full. For the good ending's epilogue, you actually want to fill it past what it claims is the cap.