This probably falls under the category of "too obvious to be worth mentioning", but I'll mention them anyway, because they're all probably more significant then anything on your list. I would say that the biggest things a person today can do to upgrade his mind are:

1. Education (including self-education)

2. Exercise:

There's a lot of evidence accumulating that regular exercise significantly improves intelligence, memory, and learning, in the short-term, medium term, and long term, in a wide variety of ways, and that it also delays cognitive decline and memory loss later in life.

Actually, that's probably true of anything that improves your heart and lung health, by improving your brain's supply of oxygen. I know that there's been recent a study that people in their 40's who smoke tend to have worse memories then people the same age who never smoked.

-3. Getting enough sleep.