I would start with saying that its best to beach comb at low tide and concentrat on the "wave zone" from about 1 foot in the water to just a little above where the waves are breaking, unless you are sure you are the first person down the beach then look everywhere from the last high tide.  I dont where sunglasses, I feel it makes it harder to find little black things on the beach.   With that,  look for black, brown and even tan items on the beach.  When in doubt pick it up...you never know.  Go slow.  I would rather have somebody pass me then rush down the beach.  I have found some awesome finds in the "footsteps" of others.  Good luck