Creating systems with moons?

[Manok]

Whenever I create a solar system it doesn't matter where I put anything, it just goes into the orbit it wants, it doesn't matter how many things are in it, if I do, say, sun, earth, orbiting sun, I try and make a moon orbiting earth, the moon orbits the sun, what am I doing wrong?

[Darvince]

Set the center of orbits to the planet you're making moons for, and see what they're orbiting.

[Naru523]

Put hill spheres up and put the moons in the sphere.

[Dan Dixon]

Most likely you are placing the planet too close to the star which makes anything in orbit around the planet very unstable.

Try moving the planet much further out from the star and try again.

Naru's suggestion is a good one. Select the planet, check the "Hill Sphere" check box for the planet in the properties panel. This shows a sphere in which objects placed inside will generally be stable, but outside they will not.
http://en.wikipedia.org/wiki/Hill_sphere

[GigabyteWaffle]

This shows a sphere in which objects placed inside will generally be stable, but outside they will not.

Yeah, usually they'll be stable. However if you have a Star -> Planet -> Moon system and you put a submoon in orbit around the moon, even if you put the it inside the main moon's Hill Sphere, eventually it will crash into it. Just some handy info for you.

[Dan Dixon]

The Hill sphere boundary only considers the 'moon' and its 'planet'. If that planet is also orbiting a star, its effects are not considered.

Thanks for pointing this out.