In my experiance, the most effective way to keep similar words straight is to link one of them to a very memorable image/ thought. Our Chemestry teacher was annoyed by the ammound of times we misspelled the word "Standard" (standerd) in exams. That's why he asked one of us to stand in fromt of the class and than gave him orders how to move his limbs to assume a frolistic stance and declared: "Das ist eine 'Standart'" (This is a 'manner of standing'). I never misspelled "Standard" again.
You can use the same aproach by inventing fun scenes or chains of thought that contain one of the words and can only be applied to this one. E.g. picture ham that sinks in a sink. "Siehst du den Schinken in der Spühle sinken ..." That does not work for "shicken" and thus you will know that ham is "Schinken" and "schicken" must be 'the other one' aka. "(to) send". But you have to invent these images yourself for them to work best.
[Edit: The easiest way for a language to reach your brain is for you to hear it. As suggested here, hearing the words used in their respective context repeatedly helps you distinguish and learn them. Studies suggest (thought I only have German references) that this even works when doing something else and hearing the language in the background so have some texts that contain either or both words on repeat while you do chores/gaming/exercising/...]
 In canse this sentence sounds odd and you have trouble understanding it: It is a referes to a (sort of) proverb: "Siehst du den Spieß im Moore winken, wink' zurück und lass ihn sinken" where "Spieß" referes to a military training supervisor and the sentence translates roughly to "If you see the supervisor wave in the marsh, just wave back and watch him sink". Don't ask me why though, I just heard it and found the stream of speech quite memorable. You can find any other rhyme or picture to memorize things so if this troubles you, just ignore it and make up something else.