The very finest way of doing it is to pump hot oil at working temperature through the engine for half an hour before you start it, every time. That's what some of the more advanced warbird operators do, though it really is a very high standard of mollycoddling. Bristol Mercury engines are not thick on the ground though, so you can see their point. If you can get the oil and indeed the whole engine up to temperature before it starts turning, start-up wear will be negligible. The main issues are the viscosity of the oil when it start pumping, and the clearances on the engine.
The colder the weather, the greater the benefits. If it is a 30 degree summer day in the UK, your oil is nice and thin and runny - even the straight-weight W100 that our Yak uses will get straight to the task of lubricating the engine. The oil pressure comes up quickly, and it does not go too high. (Oil pressure relief valves have been known to stick causing excessive oil pressure to break something - usually the pipe downstream of the pump.)
If it is winter, even the winter-weight W80 is pretty reluctant to move round the engine at 0 degrees celcius, and the oil pressure takes longer to arrive. It also takes a lot more ground running time to get the mass of the engine up to a proper working temperature, and all that time it is not only burning fuel but also more stressed than when it is thoroughly warmed though. It also takes less prime to start, so there is less risk of hydraulic locking and less petrol washing the oild film off the bores. So heating the oil before you start is a Good Thing, and heating the whole engine is also helpful. Unless you have a massive pre-heater unit of the type they used to use in airline service, it is actually far easier to use a very modest heat source to prevent the engine getting cold in the first place. So in the winter we put the aeroplane away in the hangar, close up the gaps and holes in the cowling, you can wrap an old duvet round the cowling if you want, and wire up small low-powered electric heaters to keep things from getting cold. Tactics include fish-tank heaters in the oil tank, or (better) electric heating pads that go right around strategic areas. The oil tank or sump (depending on the oil system) is the most important part to keep warm, but if you have insulated the engine compartment keeping the oil warm keeps everything reasonably warm. The cost of the electricity is pennies, it more than pays for itself with just the saving in fuel for the warm-up. And it keeps the engine in better nick! (By the way, it helps car engines live a long time, too!).
For us this is really a priority in sub-zero (celcius) temperatures, and personally I think it's worth while in any ambient temperature below about 10 degrees C.