Welcome feng.
I'm sure you've looked here:
100+ hypermiling / ecodriving tips to increase gas mileage - EcoModder.com
As for specific Prius tips, starting out I'd say for around town motoring your goal should be to maximize the amount of engine-off coasting you do. Pulse and glide is particularly easy to do in a Prius, and it can return amazing results in nice weather & traffic conditions.