The Lazy Person's Guide to Personal Finance

Credit Cards

If you can't pay off a credit card balance each and every month, then don't get a credit card.

If you can and will pay off the balance each and every month, then get a card that pays you a reward for using it but doesn't have an annual fee.

Credit Score

Pay all your bills and pay them on time.

Investing

Invest in low-cost index funds.

Retirement

Contribute to your company's 401(k) plan up to the company's match. Then max-out a Roth IRA.

Car Buying

Buy the smallest-class car that fits your needs that is two to three years old and is among the top three with the least lifetime costs for its class.

I can't in good conscience tell you that the above is all you need to know, but those are the basics. In reality, personal finances get a bit more complicated than that, since they need to be tailored to each person's specific circumstances. That is why you should really take the time to read one of the many quality personal finance books out there.

That being said, if you are lazy and don't want to spend time learning the details of how to refine your personal finance needs, you'll do a lot better following these lazy-person rules than doing nothing at all.