Credit cards business competitive, so find a niche
Sure, this is a very competitive business, but if you choose your keywords carefully, and you always need to do that, you can get yourself into a little niche. As always, find the market first and then find the product.
One way to market credit cards is to look for people with special interests, like cycling, sailing, golf, mountain climbing, dogs. Any special interest. These people are always ready to buy something related to their hobby, and you can find credit cards that can have a picture related to your favorite hobby on it.
Special interests
This is a different way of marketing credit cards, and it works for some other products as well. The idea is to find a product that almost anyone might want and market it to a special-interest group. How do you do this? One way is with Adwords, but that can be expensive. Another is to seek out forums and have a signature that advertises the credit card. This is usually the only form of advertising allowed in forums, but it can make sales, and also get people to your website.
Yes, it is a good idea to have a website to promote credit cards, but again it must be targeting a niche to get ranked. It is not a good idea trying to ranked for 'get a credit card' as you will b competing with about 1.5 million sites. On the other hand, I found only one website marketing credit cards for dog lovers. Here is a great market, not big, because most dog lovers don't know that you can get a special credit card of this type.
How you get paid
Credit card companies either pay quite a lot for each sign-up, or will pay you less for leads. Lead generation can be a good way to go, because many more people sign up as being interested than actually get the card. By getting paid for leads you are no longer concerned about the ability of the credit card company to convert leads into sign-ups.
The marketing is the same, in that you have to get the prospect to visit the credit card company's website, and to do this you will need to give them an incentive, or rely on incentives given by the credit card company. You can easily work out how much you can give away to get a prospect to the site, and then buy an e-book, knowing that if you get, say, 20 leads, the e-book will be paid for.
This is one of those markets where you need to think a little about your marketing rather than just jumping in. However, if you do, you could find this very profitable indeed.