Work on family harmony. Nothing troubles children more or makes it more difficult for them to be happy and productive than family problems at home. If you and your spouse are engaging in rabid arguments every night or if you belittle your kids, this behavior will undoubtedly affect their school performance --- they may feel insecure, lack self-esteem, feel less motivated to do their academic assignments or feel more inclined to act out to get attention. Getting good marriage counseling and committing to respect your spouse and children are a couple of ways to increase your family harmony and help your children be happier (and do much better in school).
Keep a regular schedule. Young children thrive on routine. Even if you are not the world's most organized parent, you can still keep a regular enough daily schedule for your child's sake. Set a regular bed time for your children and have them get up at the same time every morning. If possible, eat the evening meal together regularly as a family. Small daily routines like this on the home front can help children be more focused and in step with the schedule at school, hence improving their academic performance.
Focus on good health habits. Sleeping, good eating and exercise habits make a huge difference in a child's grade school performance. Children who get 10 to12 hours of sleep at approximately the same time each night will have better brain function and be more alert during school hours. Giving your child a healthy breakfast (like scrambled eggs, whole grain toast with peanut butter and a banana) provides him with energy to do well in school and to not be hungry and lethargic as the morning goes on. Finally, encourage your children to exercise; regular aerobic exercise helps the body and mind to function better.
Read together. Cultivating an interest in learning, even at home, can help your child perform better at school. Instead of watching television together in the evening, check out books from your local library and have family reading time every evening. When your children are old enough to read, let them take turns reading books while the rest of the family listens. Ask them to explain the passage that they have just read aloud. Incite the other children to participate in a discussion or to ask questions. Such efforts will promote reading comprehension and build listening skills.
Help with homework. Children whose parents care about them and their studies are almost always the ones who perform better in school. A child needs encouragement and occasional direction to finish his homework and be prepared ahead of time for classes. If you help your child study for a test, quiz him on his spelling words, ask what he is learning about in social studies class, or work with him through some of his math homework, he will perform better in school than if you show no interest in his schoolwork and academic life.