Generally speaking, the need for handshaking is dictated mainly by the capability of both endpoints to process all characters atthe iven baudrate. A good example are modems - you most probably set the PC-to-modem communication speed to 115200baud, while the modem barely can transmit half of wha the PC can throw on it using this speed... So to prevent data loss some "throttling" mechanisms have to be used - here, the handshaking are dedicated wires, pulling which the modem can signal to PC "wait a moment, I am full" - and vice versa (don't be fooled by the signals' names, they are misleading). An another way is to use special chaacters (XON/XOFF) to signal the "fullness" and spare the handshake wires, but then it must be ensured these characters won't occur in the transmitted data.

There is a third form of cables, with so called "local handshake", which is no handshake at all just a loopback in the connector shell to fool a softwa or hardware which would otherwise require full handshake cable.

But unless you don't specifically want the latter case, wiring up the complete handshake won't harm. My recommendation is to pair Rx+GND and Tx+GND and the rest random - although in reality I think this arrangement is as good or bad as any other...

Jan Waclawek