Differential equation into circuit and back - good book
Actually, try to use your basic circuit analysis methods and combine it with basic equations which you know about the components. 

For example, 

Current through the capacitor is:   

Voltage across an inductor is:   

Simply use and manipulate these two equations to get your math right. For example, look on a low-pass RC filter:



Brush up on your analysis methods and do KCL analysis... and voila! you got your diff eq. With all honesty - it always comes down to knowing the basics - and then connecting the dots.