How do you know when to use ESE instead of eso, and este instead of esto?

Answer 1

Ese perro. That male dog.

Este perro. this male dog.

Ese and este are followed by a masculine noun.

Answer 2

Eso and Esto are neuter pronouns. This would mean that they are used for concepts that are not associated with a particular gender. An example of when to use these two words would be the folllowing:

Que es esto? (When you are not sure of what the object is that you are asking about.)