It's very simple, i don't use anything special at all.
#1 Cover all electrical devices with bags ( alternator, fuse boxes, ect.. )
#2 Test the cleaner on a small area before you spray the engine down with it. ( I use Simple Geeen )
#3 Spray engine with cleaner and let sit for a few minutes
#4 Wash engine with a towel ( I use the MF towels from Wal*Mart )
#5 Scrub hard to reach areas with an old tooth brush
#6 Rinse engine with a steady stream of water
#7 Repeat steps 3-6 as needed
#8 Dry as much of the water with a towel ( I use the Absorber )
#9 Remove bags and clean the covered parts by hand with a damp towel
#10 Close hood and start car. let idle for a few minutes, long enough to get warm or take it for a quick spin to help evaporate residual water.
#11 Apply you favorite dressing to the plastic/rubber parts and buff out to a nice satin shine.
#12 If you have corroded aluminum/metal use a polish to help remove it ( i like mothers mag and aluminum polish, it works great on everything ) You may want to test it before covering an entire part with it. Also some parts have protective coatings on them to help stop corrosion, the polish will most likely remove this coating. If it does it may result is rust or corrosion so be carefull.
#13 If the paint looks a little dull i'll spray some QD on a MF towel and wipe down the paint
#14 Stand back and enjoy.