If you budget well and can pay off all your debt (except maybe an auto lease), your score will likely improve since this factor is over a third of your score and impacts it greatly. If you can then maintain a good history and make any payments on time or early, you will probably see additional improvements in your scores.
Generally, if you have a bad score, you will pay higher interest rates when you borrow. For example, if you get a new car, bad credit history often impacts other things like your auto insurance. And, in some cases, your bad credit may stop you from getting a job as many employers now do credit checks before they hire someone.