We'll start with derogatory marks like collection accounts and judgments. It's not uncommon to have at least one collection account appear on your report. I had two from health care providers I used after having a heart attack; my insurance company was extremely slow to pay and kept claiming it had paid while the providers said it had not, and eventually the accounts ended up with a collection agency. At that point, I decided to pay them right away and argue with the insurance company later, but both collections wound up on my credit report.
Making your credit payments on time is one of the biggest contributing factors to your credit scores. Some banks offer payment reminders through their online banking portals that can send you an email or text message reminding you when a payment is due. You could also consider enrolling in automatic payments through your credit card and loan providers to have payments automatically debited from your bank account, but this only makes the minimum payment on your credit cards and does not help instill a sense of money management.