The easiest way to do this, since it is between 0 and a number, is by dividing the number by 2.
So the numbers we get between 0 and 3/4 are 3/8, 3/16, 3/32
Similarly between -5/11 and 0 are -5/22, -5/44, -5/88
Note: You can similarly find other rational numbers between them by dividing the given number by any number greater than 1.