It's on every application you've ever filled out: References. But who should you use? It can be tricky choosing the few who will give your job recommendation. It is worth considering that the most effective references you have may not be those to whom you are closest, but those who can best judge your abilities and articulate them with the most impact.
If possible, choose someone the hiring manager can respect. For example, if you are a nursing student, one of the best references you can provide would be one of your nursing instructors. Pick reliable, knowledgeable, and smart individuals. This is a short way of saying that your recommendation's opinion must be trusted.
Though it may be difficult to manage, if you can get your current manager to vouch for you in the vein of "We sure do want to keep him/her, but here's why she/he is so valuable.." it can leave a great impression on the hiring manager. If that is not possible, look for a peer or mentor within your organization.
Don't forget about past managers. Pick one that is likely to compliment your skills and abilities. The whole point is to make sure that the hiring manager is certain that you know what you are doing. Because past managers make excellent recommnedations, you can see why leaving jobs on a positive note is so important.
If you are out of options and lack any of the above references, try to find a respected and active member of your community.
People generally need another person's validation of their choices, so it's no surprise how important picking the right person to recommend you is. Good luck with your job search!