Start by watching the math videos from Chad coursesaver (don't think they're available at the moment from chadsvideo.com) to get the basics down. Then do practice tests from math destroyer and understand each problem really well.
You'll have an on-screen calculator on the test but depending on which testing center you go to, you might be taking the test on an old computer with a slow responding calculator so try not to use a calculator when doing practice problems. Get good at approximating numbers and time won't be as big of an issue 🙂
Also, memorize the formulas in math destroyer and some common conversions:
F = 9/5 C + 32
2.54 cm = 1 inch
3 feet= 1 yard
12 inch = 1 foot
5280 ft = 1 mile
1760 yards = 1 mile
1 mile = 1.6 km
1 kg = 1000 grams
1 kg = 35.27396 oz
1 kg = 2.2 lb
2 pint = 1 cup
4 cup = 1 quart
4 quart = 1 gallon