I will try to add a little to this... I am by no means a pro at using them.. but I have used them a lot..
First thing.. YOU HAVE TO HAVE REALLY GOOD VENTILATION.. (ie not a fan and an open window.. CLASS A.. if you talk to an HVAC person).. NEXT.. You HAVE to wear a respirator...not a dust mask either..
I really like using the little sifter that Thompson sells.. it allows you to really place your enamels on evenly and you don't get as many clumps as you do when you roll your bead in them. Start by using the opaques.. and use the transparents as you work more with them.. I find layering them can be a very cool effect too. I don't mix them before hand to come up with a blend.. but I have heard others that really like doing it that way.. Raking them in after they are applied or super heating and allowing your bead to droop to blend them works neat too..
Also, they work wonderfully with silver foil..
After you work with them for awhile you will be able to control the application more, whether you are sifting or rolling..
I just can't emphasize enough to use proper safety precautions.. have fun with them! They really add a lot to our color palette.