What are the two factors that affect the amount of friction between two objects?

Friction is determined by the formula Friction = μFN or alternatively Friction = μFGcos(θ).

Therefore the two factors are: (1) the coefficient of friction that depends on the two particular materials (μ) and (2) the normal force operating on the object that is pressing against a larger surface (FN / μFGcos(θ)). Normal force itself has three components upon which it depends: (a) the mass of the object upon which the force acts, (b) the gravity of the body on which the events take place (usually Earth), and (c) the angle of the surface as it deviates from a straight horizontal surface.