The most common issue I’ve seen with the DSLR LCD screen is that it will get smears of your hands and finger prints very easily. It also attracts any small amount of oil excreted by the skin and constantly getting it of off is annoying. You can go an get an after market plastic screen protectors and put them on your screen but they will also suffer from scratching and smears.
One method is to use a protector screen that is available for mobile phones such as HTC and iPhone. These come in various different styles. I got the one that not only protects the screen but also prevents glare. I simply cut it out to the shape of my camera LCD and stick it on the LCD after giving it a nice clean.
Now the Camera LCD is protected nicely and doesn’t smear so the previews on the LCD are clean and crisp. Also works well outside in the sun as the screen protector prevents glare.