If you use a regular garden cucumber, peeling them is a good idea because the skin is thick. However, the skin is where a lot of the nutrients are. If the skin has wax on it, scrub it off. That will make it easier to chew. Also, slicing it paper thin will help. But the best thing you can do is to use an English cucumber. They have fragile skin and little to no seeds. They are also sweeter, with hardly any bitterness at all.