You needed more money and so you got a part time job along side your full-time job.
1-Have a goal of what you will do with the money from the part-time. For example: pay off $5000 of my student loans. When you get your paycheck, close your eyes and pay that bill like planned.
2-Write down your schedule in your cell phone and/or write it in your planner or on a piece of paper; whatever form you are most comfortable with. A written schedule will keep you organised so you know where you are supposed to be and at what time.
3-Write down the hours you worked and compare that to the hours you are paid for. Yes, companies make mistakes. If there’s an issue bring it up to the correct person as soon as possible.
4-Do your best. Just because this is your part-time job it does not mean that you should goof off, you need to complete your work to the best of your ability.
5-Take care of yourself. Get adequate sleep, eat good food and do one thing just for you at least once a week.
6-Remember why you decided to do this. There will be many days and nights where you will want to quit. At that point remind yourself about why you are working this part-time job and remember that it is temporary and will end soon enough.