Two point masses m and 2m are kept at points A and B as shown. E represents magnitude of gravitational field strength and V the gravitational potential. As, we move from A to B

E due to point mass is      $E=\frac{Gm}{r^2}$

As $r\to 0, E\to \infty$

So, just over the point masses, $E=\infty$. Hence, in moving from one point mass to other point mass, E first decreases and then increases.
V due to a point mass is     $V=-\frac{Gm}{r}$
As $r\to 0, V\to -\infty$
So, just over the point mass, V is $-\infty$. Hence, in moving from one point mass to other point mass, V first increases and then decreases.