Apologies is this is the wrong forum; point me to the right one if that's the case.
In this particular case, I'm studying limits (in an intro Calc course, and on Khan Academy) but the question applies to any problem-solving that involves algebra. I seem to make an inordinate number of minor errors in evaluating algebraic expressions--somewhere on the order of 1 error : 2 problems. The most common is dropping a negative sign along the way, or incorrectly reducing a simple fraction.
Now, it seems obvious that the answer is "practice", but I am concerned that I have some kind of bad habit that I keep practicing, since I am assuredly practicing a great deal, and keep running into this issue.
What steps can I take to stop making these errors, and to catch them before I hand in the tests?