The link below is more about repairing fiberglass, other composites and windshields. As an IA you may be referred to regarding the correct procedure for repair or be asked to inspect a repair in progress, AC43.13-1b will aid in that process When inspecting composites one should use the tap test, the handle of a screwdriver would be most ideal. Tap the skin and check for a sharp report. Any dull sound is an indication of delamination and should be investigated further. Cracks can appear in "Gell Coat" or other surface finishes, these can allow water to enter and the subsequent development of mould which can cause a breakdown in the matrix. Cracks can occur around stressed areas or areas involved in hard knocks similar to the wing hitting a hanger door. The "Gell Coat" is an extremely good witness of damage and will crack easily on impact with hard objects. Check all areas venerable to knocks especially the leading edges and tail surfaces; tap the entire aircraft and wings. Sight along the wings and body surface, irregularities should show up more easily. If the aircraft owner is a bit touchy about a hard object being used remind him you are only ensuring his safety, or alternatively use your finger tips to tap the surface but remember they will help to dull the report so listen carefully.
Windshields should not be so scratched as to cause vision loss or serious sun strike, none the less they can be polished back to acceptable levels, the method for this is described in the following AC.