Setting yourself up in an ergonomic typing position is a good start. Take a look at the diagram here - notice the arms in a straight line, feet on the floor, etc.
In my experience most people tend to slow down when they get to unusual keys - numbers, symbols, punctuation, etc, so maybe some focused practice on those key combinations? practice typing out long strings of numbers and symbols, maybe try to use some Perl code as your copy-page :)