What can I do if I don't get a phase separation between my organic and water phases?
One such cause, where separation does not take place is the nature of the organic solvent. Its better to check the miscibility of the solvent with water. There are several websites, where one can get this info. For example 1 and 2.

Even with hydrophobic solvent, if the problem persists, one can add NaCl and then check the separation.