All you do is open the dictionary to a random page and look at any word, then close your eyes and try to come up with how you would define it if you were writing it, then open your eyes and check. You will be amazed at how hard it is and how wrong you can be. Last night I sort of got "protocol" right, but then who knew there are three different definitions for that word?
The best thing is you can play in the bathtub without fear of being electrocuted, which is what happened to my paternal grandfather when an electric shaver gave him a heart attack. (It's a long story.)