Timely topic...
Your FIRST line of defense against logging refrigerant in the condenser is properly setup condenser fan cycling controls. I've heard both pro's and con's of using them, but I'm in favor of cycling the fans off during low ambient conditions.
The ORI/ORO (A8/A9 is what I typically see) setup is to manage and maintain proper liquid pressure in the event that one of those controls fail.
Setting those valves is fairly straightforward. I like to go high on the ORI valve, then dial back to the pressure that I want and go low on an A9 and dial up to the pressure that I want. Just seems to make for a more accurate setting that way.
WHERE you set those valves is a whole topic unto itself.
A more specific question or questions is bound to get a more specific and accurate answer.