Oh My! Look at the length of this string and I am just getting around to telling you to watch out for your fingers! I may have to revoke my self appointed title!
As far as safety tips, I have my usual rant about using jack stands, chocking the wheels, having another person not under the car who knows how to use a floor jack around at all times. The other point is that make sure the engine does not drop or shift such that it amputates a finger that is positioning a mount. This means that the ols 2X12 that Larry suggested could be a precarious situation that tumbles off right when your finger is in the way. The right way to do this is have two other 2X4's positoned to wedge the engine against each of the fender wells. Home made equipment is acceptable, does think about what could go wrong and plan for it!
How did I do Larry?