it's also good practice to not take the nut completely off, but leave it threaded on by 3 or so threads at the bottom. this will allow the balljoint to become unseated but not come completely out. sometimes when the tapered end of the balljoint pops out it flys and you wouldnt want to damage yourself or your car.
also, if you plan on replacing the balljoint, you can use a pickle fork and a hammer to unseat them. this may damage the balljoint or the seal, so if you plan on re-using them, dont try this method.