I'm currently working on a linear algebra heavy linear programming model for an optimization thesis and the general trick is, as with writing code, to improve iteration by iteration of the model. Starting with a complex mathematical model is always a bad idea, so start small and iteratively improve it. This means no use of advanced concepts unless needed. Also, nobody uses every bit of math in the everyday work. As with programming, you just need to understand the general concepts and the rest can be figured out step by step.