Of course there's no way of using a similar computer model as that which is used by FICO because the model is a secret, but a rough guide is useful in that it will tell you what is considered important when it comes to credit scores.

Here's a rough guide to how FICO scores are calculated:

Your payment history: 35%

How you pay your bills is important. Paying bills late, having an account sent to a collection agency, or a declaration of bankruptcy will adversely affect your FICO score. The further back in time the problem occurred, the less weight it's given. This means that if you paid your electric bill late a month ago, it's worse than if you declared bankruptcy six years ago. What happened a month ago indicates your current financial situation.

Your outstanding debt: 30%

When you're applying for more credit, the amount of money you currently owe is important. If you have several credit cards on which you're close to the limit, this adversely affects the score. Low balances on your cards helps: it shows that you're managing your money.

The length of your credit history: 5%

The longer a credit history you have, which shows prompt repayments of your bills and that you've been paying off your loans, the better.

Recent inquiries on your report: 10%

If you ask a company to lend you money, they want to know who else you've asked. If you have recently applied for many new accounts, that may negatively affect your score. Promotional inquiries don't count – those inquiries you make because you were offered an inducement or something free, are not calculated as other inquiries are. After all, you may just have wanted information and the freebie.

The kinds of credit that you use: 10%

What kinds of credit do you have? Any loans that you have from finance companies usually lower your credit score. This is because finance companies charge higher rates of interest, and people don't get loans from finance companies if they can get a cheaper interest rate from a bank.

If your credit score is low, you'll have problems getting a loan

If your credit score is much lower than the average of 750, you'll have challenges convincing anyone to give you a loan at an affordable rate – or even any loan at all.

Your credit history can vary from bureau to bureau, and so can your credit scores

The are three main credit bureaus, Equifax, Experian, and TransUnion are separate companies and they're in competition with each other, so they're trying to generate the most accurate credit scores. This means that the scores the companies give you may vary, often widely, depending on how they've applied the FICO information. You may have a high score with one and a low credit score with another, and you can have a good credit history with one bureau and a messy one another bureau. There shouldn't be a big difference in your credit scores with each of the bureaus, but sometimes your score can vary by up to 100 points. Therefore someone who's working out whether they should give you credit will use the middle score. This won’t help you much if all three scores are low, or if two are low, and one is 750 – because the middle score will be used. Usually someone with good credit will have scores like, 695, 710 and 750.