I’m afraid that my voice is abused from lack of use but I still find the process of making characters with your voice really intriguing! I particularly admire audiobook narrators who can convincingly voice a whole cast of characters, female, male and non-human alike, without taking you out of the experience. Maybe someday I’ll stop being a coward and try this.
Consider the register (deep to high pitched), the accent and the expression for each character.
Your voice is a muscle that needs to be taken care of. A warm up loosens the vocal chords.
Practice enunciation by doing enunciation exercises. Exaggerate the shapes that your mouth makes.