My advice would be to network, network, network. All the part time opportunities I've found have been through a friend's referral.
It's been essential to helping me balance my workload while launching my latest project (we're doing our "Show HN" right now actually, haha).
Meetups, a night out at the bar. This stuff is all great if you have an inclination for it. Just grab contact details from the people you meet and stay in touch. Then the opporutnities will start to flow! Good luck :)
