With regard to script, the usual question is, “How do I say this?” Proceeding from this question, actors develop a literary interpretation of the words and then base how they say the lines on that interpretation. Unfortunately, this process often yields artificial line readings that don’t sound like real talk. For your monologue to be believable, it has to sound like a real human being speaking to another human being. Period.
Okay, if you should not interpret and verbally manipulate the language, then what should you do? Answer: use the amazing mouth machine.
Though you probably haven’t noticed it consciously, you use the amazing mouth machine all day, every day. Any time you say anything to anyone, your mouth, not your brain, makes up how the words are said. In a real conversation you don’t mentally preview what you are going to say. You don’t consciously decide how to say the words. Your mouth simply blurts out whatever you’re going to say. And, by the way, it does so brilliantly.
So, the first step in the script development process is to let the mouth machine spill the lines pretty much however it wants to. Granted, at first this may run contrary to your interpretation of the lines but at least it turns the lines into “talk”. If you can do this with someone present, all the better. Engage them nonverbally, sense when they’re ready to hear the next line and let your mouth spill the line however it happens to.
How the amazing mouth machine creates the line is based primarily on whom you are talking to, rather than the meaning of the line. If you were to say the same line to five different people, your mouth machine would say it five different ways. Even if you say the same line to the same person several times, the mouth machine will say it somewhat differently each time. This all happens automatically.
So let’s assume that you have memorized your monologue. You let the mouth machine deliver those lines to another person several times (at least 10). In each run through your mouth machine says the lines differently effectively turning the lines into “talk”. However, there is an unexpected benefit to putting yourself through the above drill.
Next… Making the words mean something.