I feel like my knowledge in finding limits of multi variable functions has a few loose ends and was wondering if anyone here might help me tie them up. I have no problem performing the various tests; if for example we wish to evaluate a limit at the origin of a function f(x,y) you can let the f approach (0,0) along the axises, a line y=kx, a curve y=x^2 and so on. But that's kind of the thing. I feel like I'm never entirely sure what tests I should use or when I have enough of them agree on a specific limit to be able to conclude that that is indeed the limit. I generally resort to graphing and that works, of course, but is there a systematic way of approaching it with just the function definition, a piece of paper, a pen and a glaring lack of artistic talent?