Ask your child what type of math problems or overall math lesson she is being taught at the moment. The answer to this question can make helping out much easier for you as a parent versus attempting to help without any preparation or foreknowledge. Try to get a specific answer, as opposed to a vague answer like "algebra." A specific answer might be multiplying variables or solving equations using the quadratic formula.
Read the math problem or problems the student is working on carefully and aloud. Your goal is to talk it out with your child and get him moving in the direction of solving the problem, not to figure out the answer in your head quietly and simply give it to him when you're done.
Determine if there is any math formula or specific concept that is necessary to compute the math problem. Ask your child as well to confirm whether such a formula of concept is necessary. Again, an example might be the quadratic formula for equations or the midpoint formula for graphing.
Implement the formula or concept within the problem. Guide your child in implementing the formula by trying to get her to announce the steps as she goes and only encourage her in the direction of the answer, not giving her the answer or completing the steps for her.
Check the math problem aloud with your child after he has found the solution. Again, refrain from doing the math, including the checking, for him. It's OK to read it with him aloud, but the act of checking it for him will only deprive him of the learning process.