How to avoid talking over others when using different send/receive frequencies? Related to this question about flight services: when I talk to FSS over the generic or the local receive-only frequency while listening to the VOR voice channel, how do I avoid talking over others on the same frequency?

Intuitively, I'd listen to the frequency I'm going to be transmitting on for a bit, then send my request, and then wait for a reply on the other frequency, but that seems like it would be distracting to configure in the radio.

So how would I configure my radio for contacting FSS in this way?

Edit: this is specifically about the case where other aircraft do not necessarily hear the controller speaking to you, so they may start transmitting at any time while I'm receiving the response.
In the specific case of a flight service receive-only frequency you will be able to hear other aircraft transmitting in that frequency (you still listen to your com radio, so treat the transmitting part just like any other transmission and wait for a break before you key the mic). 

In the more general case when you have one controller (or Flight Service Specialist) working multiple frequencies you call in when the one you're transmitting on is quiet (and in the case where you're receiving Flight Service over a VOR wait for that to be quiet too).

The controller or FSS will answer you if they're free. If they're busy on another frequency or a landline they'll respond with "Aircraft calling, stand by" (or if they're really busy and don't hear you you won't get a response and you'll try again in a minute).
It's not a perfect system, but it works pretty well most of the time.