1. CEF - required to be on the routers to support MPLS
2. #no bgp default ipv4-unicast - used to disable the default behavior of putting "unspecified" commands into the AFI ipv4 unicast. This means, you have to manually go into the AFI and make your configurations.
3. If you don't advertise the WAN link then you have to source your pings from the loopback because there's no route back, since it's not being advertised.
4. BGP Next Hop Self - know when and why you need it.
Most of this is stuff I know but can forget if rushed :)
