What is the fastest way to fix credit?

It will take some time to fix credit credit and improve your credit score.
As Ryan has suggested, make your payments on time, try to repay your outstanding balances as much as you can.
Be current on your secured loan payments, if any.
Pull your credit reports and dispute errors, if any. This way also score can be increased.

I know that making payments regularly without fail can help fix credit report.

Make regular on-time payments , check your credit report for any errors and fix them, contact your credit card company and ask them to raise your credit limit if possible. Apart from that, try to lower your debt-to-income ratio.

There is no fast way to fix credit. Period. Lower your credit-utilization ratio to increase your credit score. But this isn't easy. You have to pay off the balance on your credit cards. Don't pay off the entire balance and close the account. Once you close the account, you lose the entire credit history. This again drops your credit score.