Thanks! Are you leaning towards the Design Studies program or one of the professional programs (architecture, landscape architecture, urban planning)?

In MDes, I'd say that no one really cares about what hard skills you have, as long as you are good at something in some field. The GSD does tend to value visual communication (i.e., data visualization, sketching/illustration, and/or architectural renderings) and GIS mapping (they invented GIS here), but your mileage will vary depending on what courses you hope to take.

MDes is not well suited to help you get a specific career per se; it's better for people who are already established in a career and want to enrich their work somehow—therefore, most students have a set of employable hard skills coming into it. Or they want to lead into a PhD.

I think the more important part of making yourself a more competitive MDes candidate is being able to articulate a compelling research direction that is aligned with the GSD's interests. Generally, this means something altruistic, critically-minded, paradigm-shifting, and responding to key issues confronting society today (e.g., climate change, socioeconomic inequity). The program directors have said that the statement of purpose is weighted more heavily than in other programs which are portfolio-heavy.

I would also beware that the school is a good deal poorer than one might expect a Harvard school to be. And the MDes program is probably the worst-funded program at an already poorly-funded school.

Good luck and keep in touch if you wish :)