Want to take care of credit, is paying off old debt really not worth it?

When i turned 18 i went crazy with credit cards, took out about 4 of them. I eventually didnt pay them off, got charged off, went to collections. 5 years later, 23 years old, i get denied an auto loan, pull up my credit, credit score of 544. I have no idea where to start. all my debt are old, and i need to raise my credit score so i can get a loan. I feel very angry that i didnt take of my credit, i just wish i had known and been more insightful. I have started to pay off the settlements that the credit card companies want, but then i realized that tht wont improve my score anyways because its negative and paid or not paid it will still stay on for at least 7 years. I really need to improve my credit score and i have no idea where to start or what to do...can you please point me in the right direction?