I soldered some of these things on the connector:
(the small pins to make sure it connects ok.
To avoid problems with non flat pcb’s Ive started using just small flat-end mills. I’ve had success with a 0.5mm bit. That way you don’t have the same problem as with a v-bit that as you go deeper the path gets wider. See my post here: A150: first PCB with CNC module - #4 by brvdboss
But it does take some careful testing to get the speeds and feeds right to avoid breaking your bits 