I have a few thoughts, based on interacting with kids at our club meetings and at outreach events.

Have him bring along a similar age friend who is also interested in space. The interaction between them will help make the experience "stick".

An easy trap to fall into (for me at least) is to immediately go into "lecture mode" during a first scope session. Make it more of a hands-on learning experience for your cousin. Ask him leading questions that get him thinking about how the night sky appears to moves, what a telescope does, and the like. Let him actively help set up the scope and locate targets to view.

Download and print out a copy of the latest free chart from skymaps.com. On the flip side there will be lists of suggested targets for naked eye, binoculars, and telescopes. Have him pick a few and try to find them. Help him only as much as he needs with this.

The Astronomical Society of the Pacific has a number of resources, including videos aimed at helping clubs improve their public outreach. I've viewed some of the videos, and they have some helpful dos and don'ts in interacting with the public at star parties. Some include specific tips on effectively introducing kids to the night sky.

See http://www.astrosociety.org/SharingTheUniverse/outreach-training.html

 

Is your cousin interested in space or does he have experience with star gazing?

I have worked with young children in sports, flying model airplanes, arts and crafts and some limited experience with them in astronomy.

Here are my suggestions for working with one or more children of any age.

• Give them something to take home with them. One of those star charts that Mark1Eyeball suggested.
  http://whatsouttonight.com/
• Have them circle all of the things they saw so they can look for them again when they get home. That is why I focus on things that are visible with the naked eye.
• Keep it light and fun. Do all the set-up work up front. They are here for the fun part, not the work part. This is not a lesson it is a star party.
• Show them some asterisms that they can pick out after they go home. Mark them on the chart. This will help them orient the chart to the sky.
• Binoculars are far more intuitive if you have some that are a size they can hold. Teach them to look at the object then to raise the binoculars into their line of sight. If there are binoculars at home tell them to bring them.
• Have some targets planned that can be seen with the naked eye. Mark them on the chart. See them with the binoculars first, then the telescope. When they leave they can look up and see what they have never noticed before. I love the Pleiades in binoculars.
• Explain what you are going to show them before you show them. Point it out in the sky so they understand where the telescope is pointing. ( "See that smudge there? That is a star nursery where stars are born. It is called the Orion Nebulae") Then show it to them and point out the pieces and parts. Mark it on the chart.
• A green laser pointer is a tremendous aid to helping them see what you are explaining. Look over there is hard. See where the green laser is pointing is much easier and is so much more exciting to watch.
• If you have a zoom lens this provides a huge WOW factor. Start on low power then zoom in. They love this. I have a Celestron 8-24. It is my most used eyepiece.
• Splitting an easy double, like Albireo, is fun. It is really fun with a zoom.
• If you know the story behind a constellation, tell them the story. Kids love stories that they can share with their friends.

Then show them how to target the scope if it can be targeted manually or show them how to use the GoTo controller. Give them an easy target and help them find it but let them do the pointing with minimal help from you. Moon, Jupiter, Pleiades, etc. Let them be successful that first night.

Just some suggestions from someone who loves working with children.

 

If he is obsessed with the moon, then you focus your attention on the moon and get him lathered up about the moon. Pull out a moon chart and talk about the moon.