That's the way I do it. As many LP sleeves are glossy on the front, you have to be careful not to photograph yourself taking the photograph! If the camera is good enough, it's better to take the photograph with the sleeve above centre of the picture, which avoids this problem.

I find putting the sleeve flat on the floor with a couple of fluorescent tubes either side, a couple of feet away, works quite well - especially if you switch them on! As Anahata says, the tripod (or some other way of fixing the camera) is essential.