[Zen]

The credit card and gaining credit points are from regular and constant use of your credit card (and paying the debt off in full).

However, when it comes to things like Kwok said, houses and cars, your credit rating will be looked at in depth and your 'revolving credit' is important. This is the money you have borrowed and is still availiable to borrow in credit and is a factor of your interest rates. So if you are planning on buying something of that magnitude it's generally a good idea to have a few thousand in revolving credit that is not currently being used (meaning balance avaliable not balance used). This includes Lines of Credit from banks and credit unions and HELOC's.