In my experience, FWIW, all the op-ups I got so far were without me asking. The last one I got I showed up at the gate as they were calling my name with everyone else already in (I did not want to leave the MLL before finishing up that bottle of Glenlivet ). So much for showing up at the gate early.
In the past, when I knew that the flight was full, or possibly oversold, and I made a smile to the GA possibly as glamorous as the one I made to my Wife when I first met Her, gently suggesting that I would be "volunteering" for the front in case it would be helpful, all I got was a terse look like "what did you expect, punk".
So in the end, my own strategy is to not worry and be happy.