We picked Chinese as our first language because we wanted to move there in the future and because Mummy speaks it - i.e. it was convenient. We picked French as a second language because it was locally available and Mummy studied it to AS level. If you have a second language - go for it!
My aim has been to teach the children Chinese like a mother tongue, asking teachers to act like a favourite auntie who doesn't speak English.
Since birth (or 13 months with my eldest) I've had weekly or twice weekly help with Chinese from native speakers playing with our children. The aim has been zero English, language and cultural immersion and JOY! We do lots of crafts, cooking, games, songs, children books and occasionally paint each others' nails.
To supplement this, I give Chinese language time to each child every day Monday-Friday with Mummy. For my baby, I just switch to talking Chinese for a bit of each day and have lots of Chinese baby books mixed altogether with his English baby books, so he chooses both to read.
With my middle child, we read maybe 10 characters a day, write a character, read a book and chat a bit. Sometimes we watch-AND-discuss a video in Chinese.
With my eldest I follow the expatriate Chinese curriculum Zhongwen for reading and writing, then use books, videos and fun activities to practice speaking and listening. Zhongwen, and many other resources, can be downloaded for free at http://www.hwjyw.com/ .
We already had the privilege of being part of our local area's amazing local ex-pat Chinese social life. Experience life with Chinese families has been one of the biggest joys for my kids of growing up speaking Chinese.
A local home educating Mum teaches many of us French. One of the resources she uses is from La Jolie Ronde