There’s a handy dandy feature on your DSLR camera that can save you a lot of heartache if you turn it off. On Canon cameras there is an option in your menu that says “Shoot w/o card”. Turn that to “off”. That makes it so you can’t take a picture if there’s not a card in your camera. The shutter will not even release. I’m sure Nikon has a fancy feature that is similar.
Even seasoned pros may have a slip up with that every once in a while. I’m not going to name names, but a certain photographer grabbed her camera really fast to take pictures of her two year old yesterday. They were really cute pictures and when that photographer went to review them in her LCD she realized that there was no card in her camera. The really cute pictures were never even taken. So sad.
Not that I know from experience or anything. Just saying.