Hello!

The simplest solution is not to advertise your networks to peer. By having no network statement under bgp config and not route-map / prefix-list with neighbor statement you are sure that no networks will be advertise. In this case you will still receive networks from your peer. If you would like not to receive anything put a

ip prefix-list notransit seq 5 deny 0.0.0.0/0

and add this to

neighbor x.x.x.x prefix-list notransit in

Your solution is good to for not advertising your networks.

Cheers,

Calin