I worked for a while for a mechanic who raced dragsters , one rule was wash your hands very well before fitting pistons also wipe the bore with lint free rag and thinner (its called clean gasoline here ) until the rag comes out completely clean then coat it with oil .
Most time consuming thing when rebuilding an engine is cleaning especially if you dont own nice things like degreaser bath tubs etc .
I use kerosene ( for heater ) to clean oring chains and gasoline to clean engine parts but keep it away from orings and seals or rubber in general , and i do it outside always , using gloves and gasmask is a good idea .
After that warm water washing with dish soap , dry well and lube .
I am not an expert though if anybody can correct me i sure could use extra knowledge .
I dream of owning this machine
https://www.youtube.com/watch?v=TR11dx064QQ