The right wax is only part of the issue of getting a good wax model.
I recommend a good hard carving wax, in either a tablet form for
pendant or flat- type carvings, or tubes for ring shapes. I would
recommend a green wax for the greatest detail, although is is very
brittle in thin cross-sections. The green wax is also the "slowest"
wax to work, which is a good thing for accurate hand carving, and
offers minimal "burring". This is the wax most often used for
machining wax models. For a little more flexibility, but still great
detail, try the purple wax, which won't be so apt to break on you in
the most delicate sections. A note. It is awfully important to hollow
out your wax model before sending it to your favorite caster.
Consistant thin (slightly less than 1 mm thick) cross sections are
really important to assure a porosity free casting, and you will be
using less metal, which is getting more and more expensive.
I'd let your caster put on the sprues, as every caster seems to have
their own "best" spruing solution for casting their wax models, and
will help them assure you of a high quality casting.
The tools. This is the toughest part, besides the actual carving
technique. Everyone has their own favorite tools and techniques, but
although the waxes are easy enough to find, the right tools are
ellusive, at best.
Through the years of teaching my students to carve waxes, it's been
tough to find the right tools for carving wax. I have spend a lot of
time, money and travel to locate the tools I think are the best for
wax carving, and I have them for sale on my website:
www.whaleystudios.com. You are welcome to check them out. I'm still
developing other tools that will help make hand carving wax models
easier, faster, and more accurate and will put them up on the website
when they are available.