Mac.sis making macs and S60 handsets talk

The Mac.sis reader stet approached me with the following question:

Hey, I don't know if you guys could write about this, but I'm ripping my hair out over syncing. Every time I do it, I lose contacts.

I think my main problem may be that I need to figure out a 'sync workflow' or order that I should try to stick to in order to keep one address book as the master. When iSync tells me that contacts will be deleted, I invariably lose some.

This is my setup: Nokia 5500, Mac Address Book, and Thunderbird Address Book. I use iSync with the nova media plugin to sync the Nokia and Mac

Address Book. I export an LDIF from Thunderbird to transfer contacts with the Mac Address Book. And I'm prone to initially adding contacts both in the Nokia and in Thunderbird. The main reason I need Mac's AB is because of its Smart Groups.

How can I get them to all share the same data? This doesn't even involve iCal, Thunderbird's LIghtnign component and Nokia's calendar, but I have the same problem there.

I'd really appreciate it if you could help me with this.

Any help in the form of comments from the esteemed readership would be greatly appreciated. Thanks in advance!