The common error we make is to work on an area of weakness until it becomes a strength. The reason I think this is an error is because we can work at something forever and if we don't enjoy it we will never get good at it, proficient, but not necessarily good. Because we don't enjoy what we're doing.
I am a school superintendent, but the budget is not the strongest area for me. I know it is very important and I give it full attention when working with it. But it is not my favorite aspect of the job and never will be, that is why I think it will remain my weakness. If I worked with figures all day everyday, I think I would find a new line of work.
I enjoy people, laughing (although some don't like a satirical sense of humor), organization, finding best practices for our teachers, and sharing information. I throughly enjoy doing any of the above activities all day long, and thus feel those are my strengths.
I would rather have someone going from good to great, than from poor to average, simply because they will love what they are doing. Thats why I think as educators we need to play to our strengths, because we love doing those, rather than focusing on having people work on weaknesses and have them dislike their job, which in the long run will effect the kids.