This is one of the best cards for building credit if you have an average score

If you have an average credit score but are curious about how to build credit, you're already one step closer to achieving your goal. Improving your score starts with asking the right questions — and finding the right card to help.

For those who are not yet at their ideal credit score, Select has ranked the best credit cards for building credit, and there's one that's particularly beneficial for average credit applicants.

Below, we take a look at the Capital One Platinum Credit Card and break down why it is the best choice for people with an average score who want to build credit. (See our methodology for more information on how we choose the best cards.) But first, we take a look at what goes into a good credit score when you are building credit. 

Whether you are new to credit entirely, or you're looking to rebuild damaged credit, it helps to know what goes into calculating a good credit score.

Lenders mostly use the FICO scoring model when checking your creditworthiness, so we took a look at how FICO scores are calculated. Here is a breakdown of the five categories that make up your FICO score calculation.

• Payment history (35%): The most important factor in your credit score, this looks at if you've paid your past credit accounts on time. We always recommend you pay your balance off in full and on time to get the best credit score.

• Amounts owed (30%): Banks may think you're high risk if you use up a lot of your available credit, or credit limit. We recommend keeping a low credit utilization rate to improve your score.

• Length of credit history (15%): Generally, a longer credit history helps your score. But if you haven't been using credit long, this won't necessarily hurt you as long as the other factors are strong. FICO considers the age of your oldest account, your newest account and the average age of all your accounts.

• Credit mix (10%): You don't need to have every kind of credit, but having any sort of variety helps your score. For instance, a mix of credit cards and a car loan, or a mortgage, shows that you are an ideal borrower for many different types of debt.

• New credit (10%): When was the last time you opened a new credit card account? If it was within the last year or less, wait a little bit before opening another one to build credit. You may appear a higher risk to lenders if you open a handful of credit cards in a short amount of time.

An average credit score is generally 580 to 669. While this isn't the lowest score range, it certainly can set you back. Lenders may not approve you for some loans or your interest rate could be significantly higher. Luckily, with the Capital One Platinum Credit Card, a credit score in this range may qualify you (though every application is unique).

This is a great starter card for those building credit (or rebuilding credit) because there is no annual fee and no foreign transaction fees for frequent travelers. Capital One will also automatically consider you for a higher credit limit within six months of having the card if you make each consecutive payment on time. There is a 29.99% variable APR on new purchases and balance transfers, but if you always pay your balance off in full and on time, you won't have to worry about paying this.

For security protection, cardholders are not responsible for any fraudulent purchases made on a lost or stolen card with Capital One's $0 fraud liability coverage for unauthorized charges. The issuer also makes it easy to stay on top of your credit score with its free service, called CreditWise from Capital One®. You can monitor how your score increases with time by getting alerts when a change in your credit is reported.

A few months of diligent credit card can do wonders for your score, and you may be surprised how using your Capital One Platinum Credit Card responsibly can help you step up to a rewards card in the Capital One family. The Capital One Quicksilver Cash Rewards Credit Card lets you earn unlimited 1.5% cash back on all purchases and has a $200 cash bonus for new cardmembers who spend $500 on purchases within the first three months from account opening.

To determine which cards offer the best value for building or rebuilding credit, CNBC Select analyzed 27 of the most popular credit cards available for consumers building or rebuilding their credit.

We compared each card on a range of features, including: annual fee, minimum security deposit, credit limit, rewards program, introductory and standard APR, welcome bonuses and foreign transaction fees, as well as factors such as required credit score and customer reviews when available. We also took into account how easy it is to upgrade the card from secured to unsecured and how quickly you can get your security deposit back.

Because it's unusual for credit cards aimed at consumers looking to build (or rebuild) their credit to have robust rewards programs, we did not analyze how many rewards points you can earn in the first year. For cardholders who are looking to rebuild credit, it's more important to practice good credit card habits — spending within your means, paying your balance on time and in full — than try to optimize your points balance.