The scientific, chemical, historical, histioragraphical , and archive evidence showing the holocaust is a lie is all important, but for the purpose of talking to every day people about this, it's vital to keep it simple.
The big question to raise is: where are the non-Jews corroborating Jewish claims about gas chambers and people put in ovens alive? Supposedly there were gypsies, POWs, Poles, homosexuals, and others who were gassed and burned in these camps, yet not one memoir (outside of one by an Australian named Wyatt who was later exposed as a fraud) or high profile "survivor" who substantiates these Jew claims. At least not to my knowledge.
That is pretty breath taking, because it means Jews are so insecure about the veracity of this fairy tale that they're too scared to even bribe a goy to be part of their narrative. Non-Jewish WWII "survivors" will talk about disease, famine, possibly executions, but no gas chambers.
If Jews and non-Jews lived an event side by side, but only Jews saw the infamous method of genocide, something stinks. The only Germans who have corroborated the myth are Germans compelled by torture (Nuremberg) or legal intimidation (90 something year old men in Kangaroo courts being told to read from a prefabricated document in order to gain leniency from rigged courts).