Set a good example.
The best way to teach honesty is to be honest. Avoid lying to your child, even about difficult subjects such as illness, death, or divorce. It's better to admit that some things are hard to talk about than to try to cover them up. Remember, your grade-schooler still looks to you and your partner as role models. So have no doubt: He'll take note if he hears you tell his uncle how you managed to cheat on your taxes, and he'll be rightly confused if you instruct him to lie about his age so you can save a few dollars on his amusement park admission. Honesty does have a price, and it's worth paying it now.