Find the most stable build for a given form

Having a given form a stl, how can I find the most stable form for a print (using PLA)? Of course eventually by experiment, but maybe somebody has already made tests about optimizing the stability. Eventually I would like to find the material data for the simulation in onshape. I assume this depends on the way a part this is printed (therefore the first question is what is the most stable way to print). To define a material I need to find the density, poisson's ration, youngs modulus, and tensil yield strength. Any hint how find an approximation are welcome.