No offense intended to anyone but I nearly laughed out loud when I read this thread-starter:
So my question is, what skills are most important to becoming a proficient SEO? Programming before design? And if so, what programming language?
Not a reply, but earlier this week, from Rand:
Honestly, at this point in the SEO game, it pays to be a great business strategist, a creative content developer and a phenomenal marketer far more than an analyzer of algorithms (and this is coming from the guy who spent nearly the whole of summer '05 reading nothing but patent apps and IR documents).
Build a community, a web-based service, a blog, or an affiliate sales site and you will succeed if you work hard and pay attention to only what matters, not allowing yourself to be distracted.
IMHO the top SEO skills now include: Business strategy, usability and link baiting. (The latter can be a combination of different skills, or could just be one relatively rare skill -- e.g. AJAX programming.) A lot of otherwise really sharp SEOs never quite get the 'business strategy' part down.
Top personality trait? workaholism.