Question

What two things increase the gravitational pull between two objects?

Answer 1

Two things that increase the gravitational pull between two objects are decreasing the distance between the objects and increasing the mass of the objects. the force due to gravity is F = GMm/(r^2) where G is the gravitational constant, M and m are the masses of the two objects, and r is the distance between them.

Answer 2

In order to increase the gravitational forces between two objects,
you have exactly two choices:

-- Increase the product of the two masses.

-- Decrease the distance between their centers of mass.