Wash and dry your hands
Hold the frame by the bridge
Check which temple arm is loose
Tighten the small screw at the hinge with a precision screwdriver
Tighten the nose pad screws if the nose pads are loose
Gently bend the temple arms inward if the frame is too loose
Adjust the temple tips slightly inward for a firmer fit
Use warm water to soften plastic frames before minor adjustments
Stop if the frame feels stiff or you see cracking
Take the spectacles to an optician if the fit is still loose