The way the loan industry works is pretty simple. Loan companies charge interest on loans that they make so that they can earn money for themselves and to cover any losses they might take from people not paying back their loans. It only makes sense that if you are a lower threat for not paying back your loan that you should get a lower interest rate to compensate. Because your threat level on low interest payday loans is generally measured by your credit score, if you don't have bad credit, then you're more likely to be able to get favorable interest rates.
Something else that affects how much interest you will pay is how long it takes you to pay back the loan. The faster you pay off low interest payday loans, the less interest you end up paying total. There are two big things that you can do to make sure that you pay off your interest as quickly as possible. First, you should only borrow the amount of money you need, and you should avoid borrowing more money just because you can. The more money you borrow, the longer it will take you to pay it off. Second, you should avoid getting cash advances for longer than you really need. If you can set up your payment plan so that you will be paying the loan off in three weeks, then that's going to save you money compared to paying it off in four weeks. Even a single week can make a lot of difference.
One trick that some loan offices use to get more money out of you is to advertise low interest payday loans that tag on extra fees that aren't labeled as interest. This has the net effect of costing you more interest than the loan might be advertised for. Sometimes you won't be shown the truth until you've already started filling out paperwork, and this is a ploy to try to get you to feel committed to the loan before you have actually signed.
Some people have a bad habit of using payday loans to purchase luxury items and to make impulse buys. Even if you're getting low interest payday loans, you should try to wait on your paycheck normally if you can afford to. One big problem with using payday loans for these types of purchases is that if a real emergency comes up while you're paying off your previous payday loan, then you will find yourself in a lot of trouble since it will be harder to get an additional loan for the real emergency.
What you really need to do if you want to pay the lowest amount of interest possible is to get low interest payday loans with flexible terms that you can pay off on time. Most low interest payday loans have pretty big penalties if you're late on paying off your loan, and this is the monetary equivalent of adding on more interest.