I would recommend the red book released by the test makers. It should be the most accurate measurement. If you’re having trouble with timing, the only real solution is to practice. You may want to start without a time limit and give yourself a chance to have a good look at the question and get a feel for how you should reason out your answers. Then try to speed up. For the English and Math sections, your speed will probably increase just by learning more, especially the English. Learn the grammar rules that you make mistakes on. You should definitely learn when to use what type of punctuation (http://www.sparknotes.com/testprep/books/act/chapter5section1.rhtml gives a quick run through). For the science portion, it may be beneficial to just quickly skim over the introductory paragraphs that tell you what everything is talking about then quickly go to the questions (a lot of people even completely skip over the paragraphs, but I personally feel more confident giving them a quick skim to understand a little better). Since the questions usually specify what graph or section they are talking about, you shouldn’t have to analyze the charts or graphs before you start the questions. I think you should be fine if you just practice more. It’s best to practice just one section at a time, so that you can really spend time to specialize in each (for example, if you decide to work on english, do all of the english sections instead of going through a whole test).