Could anyone direct me to any good practice tests?

I’m looking to improve my ACT scores (specifically my Math (26) and Science (27), as my English and Reading are 33 and 34), but I’m having difficulties finding any decent online practice tests in order to prepare. I’ve been using McGraw-Hill’s online practice mainly, but I’ve found that their science section is too unlike the actual test to be very helpful. Thoughts? Links? Anything would be appreciated.