Formal art training or not a drawing tablet will certainly make sketching your ideas more humanly normal than trying to do them via a mouse. No doubt it certainly can be done using a mouse but a drawing tablet will make the whole experience more natural to you. Drawing tablets like everything else come in different flavors. But no doubt certain manufacturers have a good edge over others and Wacom has this advantage. Even copying a photograph for Photoshop manipulation becomes much easier when you can lay the original photo under the acrylic screen that comes with most drawing tablets allowing you to trace over the image with the drawing tablet stylus becomes much easier than simply using a mouse. Using a tablet you can control the flow allowing you to control the amount of “ink” being put down at any one time. And if you don’t like it…you can turn your pen around and use the other end as an eraser just like a real pencil. As far as formal training is concerned, I suggest you go to the library and start reading beginner’s books on sketching. This will definitely help in creating true to life situation renditions. Early artists had no formal training…they practiced and that’s what made them great.