It all depends on how small your tablet and how big your monitor. Your tablet small like
this one or like
this one? If the last one which compatible with the most 19'' monitor, so you don't need bigger tablet (for animation trainings), but if smaller then you better to purchase the medium tablet. But despite the size and the scraggly lines your line path roughly must be straight, if it doesn't, you should draw more. I tried to do some exercises at the first time but then I decide to draw the characters even if they looks like blotch (this happen only at the first time). After this drawings you will feel the tablet and nothing will be more handy than this great tool. I don't use the mouse about two last years, only the tablet. But if you want exercises: 1. try to draw 10-15 straight lines with 0.5 inch spread between them, 2 make some infinite symbols (or eight digits), 3 make some random or even spaced dots and then draw a line through all of them.