What really helped me improve my typing speed is... honestly? Not giving a shit about accuracy. I learned where to place my fingers and then I just typed like crazy. I improve in little steps, I type at 85% accuracy until my speed goes up, then I try getting to 95% and it speeds me up even more. Then I stop caring again until I am 10 wpm faster at lower accuracy and then I pay attention to accuracy again.
My experience has been that if you don't try to make your fingers move faster they won't move faster. So you'll have to move them faster and keep doing that until they hit the right keys.