first try this
http://vraahojskole.dk/emil/FARVE.htm

then: the mag lite is fine I think. You shouldn't be too worried about the harshness of the light beam - as you are moving the light scourse around..
BUT be carefull about the inner side of the cone.. it has to be very dark - preferrebly black. That minimizes the risk of light streaks in "the air" when moving the torch around...

for this:
http://vraahojskole.dk/emil/FA-CALLA.htm

I use a very small light torch - so small that it could go directly in the flower...
and I used to lit the beam as well (don't know whether that is the right word)

the background I then painted with a bigger 25watt light scourse...

(use Fuji RTP II 64 iso tungsten - it has such beautifull saturated colours..)