|Venus Passing the sun (source = eschipul.com)|
When you come to an obstacle, let's say a test. You think of all the ways to complete the task in a timely fashion. For all the Praxis tests, any other test for that matter, skip to the ones you know how to do without thinking, then move to the next set of problems until you are stuck with all the difficult ones.
(Note: Jumping around does not work for everyone.)
If you don't have a strategy of how to take on a particular test, then make up one quick. Most people take things as they come. If you know the answer or feel you know something about the question at hand. Answer it to the best of your knowledge. Since the results for the Praxis are calculated behind the scenes, all you can do is just prey everything is correct.
If you feel uncomfortable of taking a test in a particular subject
The "IT" is up to you decide. Life is all about choices. So make the right choice to obtain new skills.