Be Great at Your Job
Your ability to earn an income is your greatest asset. Become indispensable at work by excelling at your job and exceeding expectations. When an opportunity for promotion arises, you'll have a great case for getting the job, and if the time has come for you to part ways with your company, you'll have reliable references to back up your job search.
Do this: Write down your big wins as they happen over the year. It doesn't matter if it's in Excel, Google Docs, or a plain notebook, just start keeping track of your accomplishments. That way when you're pushing career progression, you'll be able to easily whip out the detailed facts and be able to make a stronger case of why you deserve one. After all, memories can fail, and it's easy to forget certain achievements over the course of a year.