The key with finishing any lure you cast, is to make sure you remove every trace of mold release. I wipe mine down with alcohol and was them in really hot soapy water, then thoroughly rinse with hot water.
I like to base coat with a dip of disolved plastic. The Bottom one received a few dips.
Tally made a tutorial on how to make the stuff. Propionate Pellets are better than cups and are available on Ebay or through Swede.
I use flat head nails as my guide pins. I insert them appx. 1/2" into the clay prior to pouring the first half and make sure I cover the heads with atleast 1/2" of whatever Material I'm using to make the mold from.
Here's a pictue of a Bondo Mold I made for Jig Heads.
I get perfect alignment everytime and I'm able to put the halves together w/o distutbing the weights and harnesses I'm casting into the castings.
I've used the hard urethane rubber, shore hardness 80 with good results. The Tin Sil Silicone looks to be a good product.
Here's an early Poes mold w/o locating pins. The material is Urethane rubber, Shore 80 hardness.
As Travis said, you can get good results from rigid (Bondo, etc) molds, but the molds must be perfect. w/o any undercuts. The Softer mor flexible rubbers allow for some margin of error, although I must say, you should strive for perfection in any even.
Freemans Tutorials are very informative and they make it look easy.