Welcome to tubing--you might check out Rob's article on this site as well. I would recommend only wearing waders in closed, calm water like a bay. If in the ocean, the chance of getting them filled with water is too great. Wear a wetsuit if going off an open beach. Pick a sheltered beach and/or a small surf day too. You can't move very fast in a tube, so outrunning a wave is impossible. I like beaches that drop off fast with a shorebreak so I am out of harm's way quickly. Higher tides are usually safer to launch as rocks are covered better. Watch as the tide drops though, I was at an unfamiliar beach and was greeted with exposed boulders in the surf line upon my return at lowtide. I had to kick to another cove 1/8 mile away and walk back.