I have been running a cherokee-6 with an IO-540, 300 HP lycoming for about a year. I sought out the advice of a very helpful guy who had run the same type of a/c as a parachute jump plane and had achieved TBO and beyond with it.
His recommendations seem to work well and my engineer agrees that my engine is in great condition, certainly I haven't - yet - had any nasty surprises (fingers crossed).
Immediately after startup, lean aggressively at no more than 1000RPM. This warms the engine as rapidly as possible, still taking several minutes, giving me time to check out all four tanks and run through the checklist, tune radios, etc.
Never exceed 1000RPM until the CHT is well off the stop.
If you are parked on grass, for a tarmac runway, pull the a/c off the grass by hand so that you don't have to over-rev to get moving.
If you've got the runway length available, open the throttle progressively rather than just firewalling it, this also stops stones, etc, being sucked into the the prop - don't forget to richen the mixture.
Although its off subject, after landing I also do a scavenge run on the engine for a couple of minutes at 1200 RPM with the mixture leaned back until the RPM just starts to droop.
The last endoscopic check showed the cylinders in good condition and the plugs just seem to go on and on...