Start with flash cards for your addition and subtraction fact families. You can purchase these at any office supply store, or you can make them yourself. Just get some card stock and cut out a bunch of triangles. Place one fact family on each triangle. For example, one triangle would have a 4, 5, and 9 in each corner. That is because 4+5=9, 5+4=9, 9-5=4, and 9-4=5.
Work on multiplication and division flash cards after your child has mastered the addition and subtraction facts. Again these can be purchased at an office supply store or made at home with index cards. Place the problem on the front and the answer on the back. For example, the front of your index card would read "3 x 5=" and the back would say "15."
Use candy to demonstrate the fact families and multiplication and division problems. Candy is important because it is something your child will take an interest in. M&M's and Skittles work the best. Place nine M&Ms on your table. Have your child take away five, and ask her how many are left. Now put all nine M&Ms back together and take away four. Then have your child take four M&Ms and five M&Ms and put them together to see how many she has all together. Ask your child if she sees a pattern. For multiplication ask your child, "If four children each have three green M&Ms, how many do they have all together?" Place three M&Ms at each chair, pretending that each chair has a child in it. Do the opposite to show division. Have your child hold 12 green M&M's and instruct her to equally give four students the M&Ms. The equation would then be 12 divided by the four students equals three.
Write out some word problems. Make sure these word problems use situations that your child will encounter in real life so that he will take an interest in it. You could say Tommy had five baseball cards and Billy had four. How many baseball cards would they have if they decided to combine their collection?
Practice the facts with your child daily, but don't practice longer than 15-20 minutes per day. If you go over your child's attention span, you won't get anywhere.
Start giving your child speed drills. After she has an understanding of the facts and has the facts memorized, she can begin speed drills. See how many problems your child can answer in one minute. Each week your child should improve several seconds until she can do the problems without thinking.
Use free online worksheets (see Resources). The Internet is loaded with free printable worksheets for basic math facts that you can use to quiz or give your child some extra practice.