If you have saved old performance appraisals or can remember specific compliments, quote from them in cover letter and interviews. Brush up on any rusty skills by taking classes or doing volunteer work. Build a strategy for marketing yourself. After determining what your skills are and the kind of work you'd like to do, consider where you might find a good opportunity. Because you're interested in more responsibility than you had before, consider the following.
Smaller companies are a good place to look.
They usually don't have many layers of management, which means more visibility and opportunity for a hard worker. Job descriptions and degree requirements are often more flexible, allowing easier entry and varied, generalist experience on the job. This is much safer if your progression is logical, if you leave for more responsibility, salary or opportunity. If you decide you want a large organization, joining a professional organization will be very helpful. Many companies pay their employees' memberships so there will be many potential contacts for you to develop.