If you're doing anything more than 2-4 layer PCBs, I'd make one more caveat... through-hole-via! It makes getting to test points much easier from both sides of the board, and if you're using pogo-pin testers, helps align the pins.
Unfortunately, if you're doing anything highspeed (>100MHz) or differential, then such vias (except at connectors) are highly frowned upon since they increase loading, crosstalk, imbalance, and reflections.
Unfortunately, if you're doing anything highspeed (>100MHz) or differential, then such vias (except at connectors) are highly frowned upon since they increase loading, crosstalk, imbalance, and reflections.