I'm surprised some here say crank with ignition off to clear any oil.
I used to part own a Yak52 (Vendeneyef M14P 9-cylinder radial) and it was drummed into us to pull it though 10 blades by hand before starting. The M14P uses air start with an air distributer which turns the engine very slowly, but even that can damage the engine if it locks hydraulically.
Also, with those engines, if it's not run for more than a few days it's cowlings off and take out the drain plugs in the inlet pipes of the lower 3 cylinders. Oil can collect there and it won't come out by hand-pulling it through as the 'elbow' in those inlet pipes is below the level of the exhaust valves. So any oil stays there 'till start up, wherupon it gets sucked into the cylinder where it can cause a lock. If you are lucky, the engine breaks there and then and you get you wallet out. If you are unlucky you bend a con rod and the engine fails some time later, and somewhat dramtically, as the rod breaks in the air one day.
There was a recent tragic case of a Piston Provost engine failure in UK. One thing that was discovered in the investigation was that some Provots pilots had waggled the prop back and forth to get oil to run out of the exhaust before start. Problem with that was that it allowed some oil to drain into the intake pipes as the inlet valve opened, with catastrophic results on start up or later due a bent rod.
Starting the Yak was definately an art. A friend once described it as 'biblical'; lots of noise, lots of smoke, and the smiting of lesser aeroplanes that might be parked in the propwash! (OK, we did ensure there were none of the latter!).