1. Make it fun
Kids at this age are very easily distracted and can have a hard time staying focused on one thing for too long. Try to find ways to make your lessons fun for these students. Play musical games on the instrument, use books with cartoons, ect... Stay positive and keep encouraging even the littlest of accomplishments.
2. Choose the right material
There are very few books out there for kids of this age, but be sure to avoid any material you would give Junior or Senior High students. Younger students learn at a much slower pace and can only learn so much at once. Find material with large print and cartoon characters that will keep the student entertained and focused. For drummers I would recommend the book "drum lessons for kids of all ages"
3. Keep it simple
Don't try to get to complex with any lesson that your teach. If you are teaching them basic technique give them 2-3 tips and know that it will take them possibly weeks to master. Teach your lessons in their simplest form, or just follow along with the kids material that you purchase and try to be sensitive to your students learning style. Modify if needed.
4. Get parents involved
Keep the parents in the loop with how the student in doing/progressing. A good idea would be to keep a lesson journal for you and the student/parent to chart progress. At this age kids won't practice without the parent constantly encouraging them. So, keeping the parents informed about what you are working on and what the student can practice is key to a students success.
5. Be patient
One of the most important parts of teaching this age is to be very patient. Young kids learn very slow and need a lot of encouragement. If the student doesn't understand the material right away, be OK with that. They won't progress like an eager high school student will, most of the time. Slow and steady wins the race!