Forget the microwave folks. The microwave will work sometimes, but not all the time. 20 seconds in the microwave one day may be fine, but on another day with the same tobacco dry it out too much. Roverblue here is my method...
I use a coffee cup warmer similar to this... http://www.amazon.com/KUWAN-Coffee-Warmer-Beverage-110V/dp/B018NZ1AXY/ref=sr_1_4?s=kitchen&ie=UTF8&qid=1458522912&sr=1-4&keywords=coffee+cup+warmer . Mine has a low and high heat setting. I use both depending on how quickly I want my tobacco. I place my tobacco in a flat bottomed coffee filter and put that on the warmer. It sits near my computer so I can browse the forums or anything else while periodically reaching over and mixing it up a bit with my fingers. This allows you to get the tobacco at just about right every time as you're feeling it every time you mix it up and so therefore have more control over the dryness of your tobacco as opposed to microwaving. It takes a little bit longer, but it's worth it in the end in my opinion.