Our brain is a master of efficiency. It is designed to quickly recognize dangers and food in the bush and savannah. Trivial things quickly fall out in comparison. Unfortunately, this also applies to Shakespear’s sonnets.
If you want to memorize a seemingly incoherent text, you have to trick your brain – and the best way to do that is with surprise. Anything that is unusual helps: You can sing a poem, dance to it, or make big gestures. All you have to do is be particularly silly once or twice in your own little room – your brain will remember it afterwards and remember the sonnet better. In any case, gestures and facial expressions reinforce what has been learned.
Extra tip: When actors have to memorize long texts, they often write only the first letters of the words, separated by a space, one after the other. This way, the letters still recall the original text, but they still force the brain to abstract it.