It’s very simple.

Read: http://en.wikipedia.org/wiki/Free_return_trajectory

Then read: http://en.wikipedia.org/wiki/Lagrangian_points

Then read: http://en.wikipedia.org/wiki/Lissajous_orbit

Then read: http://en.wikipedia.org/wiki/Hilda_family

Update: if you just want some pretty, try this video of this asteroid

Orbital mechanics rocks!