This topic has been discussed a couple of of times on this forum (not specific to RF, but the principles are the same). Try using google (with site:eevblog.com) to search for topics like test automation, gpib or lxi. You will have to decide on an automation platform like NI LabVIEW (graphical programming, which might (or might not) be easier if you don't have much of a programming background), a real programming language like Python or C#, or scripting embedded in a tool like lxi-tools. It also depends on what type of instruments you use: Are they modern stand-alone instruments with LXI, older stand-alone instruments with GPIB or mainframe-based instruments like VXI or PXI(e). You probably already have some instruments.
Depending on the type of tests, you may want to look into an RF switching matrix that can change connections under computer control. This allows you to for example connect 10 DUTS and 5 test instruments and connect each DUT to each test instrument in sequence.
There is no step by step procedure because the steps depends on your use case. Just like there's no step by step procedure of "how to design a PCB". What kind of instruments do you have? What kind of programming background do you have and in which language(s)? What kind of tests are you planning to run?