Hitler's rise:

Great communicator, who reached millions by using films, radio and rallies all over Germany (e.g. the Nuremberg Rallies)
Portrayed himself as a well capable; leader and at the same time a man of the people

Policies and slogans:

Relied on generalised slogans (e.g. 'uniting the people of Germany behind one leader')
Nazis took every opportunity to state that the Jews, communists and Weimar politicians were the causes of Germany's problems

Nazi actions:

At a local level the Nazi party demonstrated it was a party that could get things done
They organised soup kitchens and provided shelter in hostels for the unemployed
The uniformed SA and SS in the streets demonstrated to people values of order and discipline

Disillusionment with democracy:

There was deep dissatisfaction with the democracy of the Weimar Republic
Politicians seemed incapable of addresses the problems of the Depression
Chancellor Brüning relied on the emergency powers of Hindenburg, under Article 48, to bypass the democratic process altogether
Brüning did this in order to cut government spending and welfare

Decadence:

Nazis could count on those who felt traditional German values were under threat from the Weimar culture
Nazis mentioned restoring old-fashioned values for the good of society

These reasons for Nazi Party growth helped when dealing with the threat of the growing Communist Party. In dealing with the threat of the Communists, the Nazi Party received support from both business leaders and farmers.