The two ways to earn more from working boil down to working more hours, or earning a higher hourly rate. You can tack on a part-time job in the evenings or at the weekend. To get a higher hourly rate you could push for a pay rise in your current role, or try to move to a different job which pays better. Maybe adding to your qualifications would help achieve this, or maybe you’ll need to retrain for a different field entirely.