I suspect the really "lifelike" flower preservation probably takes some kind of crazy resin, probably also some antibiotic and antifungal, and perhaps some kind of antioxidant compounds.
There is a detailed manual on glycerine technique in this PDF: http://www.ksre.ksu.edu/bookstore/pubs/mf2446.pdf
I have also heard of using glycerine to preserve flowers. The challenge in the long term is to prevent colours fading.
Using "drying" kits like silica gel won't work that well with orchids, which are quite "fleshy" compared to many other flowers.
Freeze drying and embedding in resin might also work, but suitable methods are beyond home use. (I remember colleagues in my student days freeze drying small invertebrates for examination under SEM, so it doesn't distort things too badly; they used a CO2 method).