The first thing to remember when a new school year starts is timing. It is a good idea to adjust your child's schedule to the school year schedule about two weeks before school starts. This means waking up earlier, eating dinner, and going to bed earlier in most cases.
Another good habit to get into is picking up the list of required school supplies at the earliest possible time, so you can make sure that all items are purchased without the last minute rush. Buying more than the list suggests is usually a good idea, as things frequently get lost, or are used for more than just school purposes.
For elementary schools, many of them are now asking for checks or money orders made out to the teacher, and the teacher will buy the supplies. Even so, it is still a good idea to send your child with pencils, crayons, a glue stick, an eraser, and safety scissors. If the teacher asks your child not to bring them back to school after the first day, that is OK, but you know your child will have the supplies at home.
Make sure that appointments are made for physicals, shots or general checkups prior to the start of the school year. It is generally a good idea to schedule these about a month in advance, to ensure that your child is seen before the start of school.
For older children (middle and high school ages) who want to shop for their own clothes and supplies, insist on going with them, or at the very least, to see what they've bought. Many schools have dress requirements, and only accept certain types of paper and ink.
Working parents, keep in mind also that you will need to make sure you've got a babysitter or daycare lined up for young children after school, and in some cases before.
Make sure you child knows the school schedule and bus route if applicable, and let him/her/them know that you are interested in talking about their day, and seeing their work. Showing interest in your child's accomplishments is the biggest incentive they could have to do well.