Sea glass collecting is not as hard as some people may have you believe. The ability to find seaglass is not likely to disappear any time soon since human beings have yet to master the art of not littering; whether by accident or on purpose. You just need to know where and how to look. for it.
I can walk a beach after the tide has reached its lowest level and still find pieces of glass among the many foot prints left behind in the sand. I think most beach goers are there merely to enjoy the sand and surf, but I also believe that pieces are easily missed because they seem to blend in with the sparkle of the sand and small stones scattered about.
Pick a beach, any beach, and go for a walk.. Don't be discouraged if there are other folk already on the beach, or if the sand seems trampled by thousands of foot prints. The trick is to take your time; stroll, and look down. You won't find anything admiring the water or the area seabirds. What you seek is in the sand.