In these situations: Getting published or landing a talk at a well-known conference helps. So do certifications and degrees, as much as I hate to say it. A lot

In these situations: Getting published or landing a talk at a well-known conference helps. So do certifications and degrees, as much as I hate to say it. A lot of the questions asked of your references are less about what you know and how good you are at a given technical skill, and more about work ethic, how you think, disposition, and how well you work on a team, under pressure, and what you do during downtime at work. These are the kinds of thing that any previous supervisors, mentors or co-workers could answer.