I am a CS/CO. To be succesful, you need to be able to write well. It is similarly important to be well spoken, but I would say not as important as writing these days. I write emails and contract documents all day long. I know that people make decisions about me based on my communication...and I do the same...it's our currency as specialists. Computer skills are also very critical. Being an excel whiz doesn't hurt. I am often amazed that people come into this field without at least an intermediate knowledge of business (accounting and finance topics...not management). Numbers and business concepts are critically important in this field...you need to be good with both of them. Because of poor hiring practices, you could make it in the door missing any, or even all of the above. But as you progress, your weaknesses will be exposed...and you'll stop progressing. Good news (not for the taxpayer) is that it's nearly impossible to get fired once you get in...you'll just stop progressing. Still, you'll stop progressing at GS-11 or GS-12...which is much farther than a person missing skills critical to their job would make it in the private sector.