Many options are listed on the Support Page
(Green X+ button next to CP on the Sidebar)
Additionally, the Work for CPs
forum sometimes has small projects that you may be able to contribute to and potentially gain CP for.
Finally (and this requires a significant amount of time, commitment and sometimes OOC skills), volunteer for one of the Teams
that currently have need of new members. Hiring/Team Needs are usually posted to the SimNews:Community News
and vary significantly in the CP compensation they provide.