i used crc engine de greaser last time i cleaned up. it had no smell after it was washed off with a hose. and worked as good if not better then the rest out there.
you want to put the car on car ramps, or jack stands so you can spray under the car, so you can hit the sides of the engine block and pan, and the back side of the tranny. from the pass wheel area, you can spray a good chunk of the trans down too. then spray the top of the engine down, 2 cans is always a must, as one can will do it one time, if its real bad, spray it down again.
if your all stock, air box and all, you can literally spray the whole engine down with a hose, just avoid nailing the alternator with a a full blast for to long.
all the plugs and wires have weather pac seals, its all safe to get wet.
if you have a open cone air filter, take it off, bag and rubber band the TB opening.