Do not necessarily use the same finger to type the same key; use whichever finger is most comfortable, which can vary based on the context of the letters in the word. Do not type each word at uniform speed. Speed through the easier words and take a little more time on the harder words to ensure accuracy. Always focus on the word after the word you are currently typing so there are no unnatural pauses in your typing. I recommend using caps lock instead of shift to type capital letters to allow more flexibility in the hand that you would normally use shift with. Finally, with regard to online typing games, for whatever reason my scores seem to register higher in Google Chrome. Although this won't actually improve your speed, it could improve your nominal scores on certain typing sites.