Only brush twice a day...for 2 minutes each time
There has been much research done into how & when to brush your teeth over the years, and we now know that brushing your teeth too many times a day can actually cause some damage depending on when you do it. Especially if you do it just after acidy foods or drink which soften the enamel & dentine.
To cut a very long story short the advice is to brush your teeth twice a day for 2 minutes, in a morning & before bed. Use a Fluoride toothpaste, & floss after brushing if you can.
Colgate have produced some nice printable materials with some basic advice on how, when, & with what to keep your s & your kids mouths clean and healthy.