You know what is most annoying to type, other than quotations and punctuations? British quotes. It really slows down typing when you are trying to type 'color' and it shows up as an error because the quote was spelled 'colour'

When my fingers hurt after too much time on the keyboard, I stop and stretch them......and usually take a coffee break

My tip to improve your typing speed is to...take it slow at first. Think about the letters you are typing. Once your fingers build the muscle memory of each letter, you will be able to type fast without even thinking about it.