|Develop People Skills
The single most important skill for any manager is the ability to manage people. Learn how people think, react, and function when faced with different outside forces. Develop respect for people, even those different from you. Learn how to work with people and then you can learn how to influence their behavior. Nobody will promote you to a management position if you can't manage people. Anyone who gets a management position and can't manage people is doomed to failure.
Don't sit at you desk and wait for someone to hand you a management job. Demonstrate initiative. One key management skill is planning so volunteer to help your boss prepare the annual budget by collecting necessary information. Offer to help put together the estimate of what the new addition to the production line will cost. If your department has to send someone to the planning committee for the company picnic (or the employee relations committee, HR study group, etc.), volunteer for that assignment. (You will also learn valuable people management skills as discussed above.) Take on whatever you can without negatively impacting your performance of your main job.