i have had it done to me 4 times. very messy.
the first was algaesafe/seaweed. didnt really work. the stuff dries out so you have to move quick. have everything layed out, cut.
second time we tried a quick 90 sec pot life silicone from smooth-on and that was a disaster. it cured as my friend was applying it. once again, all layed out. preparred in cups eady to go.
third time was a slower like 5 min pot life but my friend wouldnt listen to some technique that i had thought about. another fiascal.
i did my brothers head next.
this was my first time applying it. fourth time around it. i used the same life casting silicone from silpack as from my third time. love it. he has a shaved clean head so it was simple. but still used vasoline on the facial hair. plucked a few eyebrows and lashes. be generous with vasoline. i started at the back of the head, top, ears, front neck, mouth, cheeks, lastly nose. think about the pattern. the nose was last for obvious reasons and i personally have not used or had my brother use straws or such. just go slow and you dont have to worry about breathing in silicone. if you are clostorphobic of any type you probably wont make it through a session. use lots of vasoline. make it nice and thick. use bandage scissors to cut it on the back. plaster bandages for a mold. two part mold, use vasoline for the mold realease. once again very thick. use warm water, i work in surgery, apply splints, trust me it works better than cold water.
fourth time me, i had my mom do it. layed it all out, a and b in plastic cups allready to go. bought a swimming cap, applyed cheap movie glue, vasoline. same pattern, came out fine. not perfect but very good and useable.
everyone sayd to have fun take pictures, i dont agree with that. i couldnt drink, sweated like a pig, it is not fun, had to be very relaxed, took around 3 hours. i never drank once when i did my brother, if he couldnt drink, i wasnt. i concentrated on doing it safely. so you can do it with one person, but if you have never seen it done then have a second person to help.
in a rush, have to go to work. hope this helps a little.