If you are in the unfortunate position of having had a bad credit experience in your past, in short you have bad credit then there are certain things you should do and certain things you should think twice before doing. What you should do is to try your very best to repair your credit rating as this will have the most significant impact on your fortunes going forward, meaning that you will end up paying significantly less on any financial commitments you might end up taking out and it will also mean that many more financial products are within your reach than if you continued with your bad credit status.
Taking out a loan, and there are a number out there which are specifically designed to be attractive to people with bad credit; for instance bad credit auto loans, is not such a good idea. The reason is simple and relates back to the first point; the interest rate you are likely to be charged is almost certainly very high, indeed bad credit loan interest rates might well be as much as 25%.
So do yourself a favor and fix your credit before taking out any more loans.