About five/six years ago I was flying Club regularly with BA and, after about every 4 or 5 round trips a nice person would be called to the check-in desk when I arrived. They would thank me for flying BA and walk with me to Departures. Invariably, I would find I was upgraded at the Pier-head.
I have now been a Gold card member for 3 years in a row, long-haul always Club, even longer haul (twice a year) First.
However, the nice people seem to have disappeared and I have not had any more "check-in"upgrades. So, if I'm no longer seen as good for an upgrade ....good luck with your tactics!!
Before you say it, I do smile and I am polite
but, I won't ask for something I haven't paid for.