Hi all, I am new to artificial neural network. Currently I am trying to solve a regression problem with 3 input variables but the ouptput dimension is around 40. I cannot get any acceptable fitting results after several trials.

Is there any general rules in dealing with this kind of regression problem, such as how to choose activation function, number of layers and neurons in each layer? I used 3 layers with about 500 neurons in each layer, and Relu activation in all layers. It seems to improve very little when I increase the model complexity.
Apart from neural network, is there any other tools suitable for this problems?

Thanks