This article will give you a few tips how to decrease a psd or AI file.
1) Delete all layers that are not needed
2) If you are using smart objects, delete or merge the layers inside the smart object. This is the biggest culprit. You want to reduce layers inside smart objects.
3) Do not use smart object inside of smart objects. This increases file size drastically.
3) Do not use any 3D elements in the design file.
4) Rasterize any layers using effects like stroke, gradients, shadows etc.
5) Rasterize any bending, warping.
5) Less layers the better , merge layers into one, if they do not need to be edited.
*remember you can keep the original design file, we only need a minimum version that can be used to insert customer photos and or edit text.