How do I improve my social awkwardness?

I can hold down conversations with people and so on. I don't feel any conscious fear of social interaction but I am always aware of my conversational clumsiness. I end up half-offending people by accident and a lot of people I work with just do not 'get' me.
In addition, I am pretty shy around women. Had girlfriends before and even been married but I sometimes turn into a thirty something teenager when in the presence of someone pretty.

Any advice?