How do I safely do these workouts so as to prevent unnecessary fatigue or pain afterwards?

Learn how to listen to your body’s signals. If you do an exercise that feels painful, awkward, or overly fatiguing to your body, stop and modify the move to what feels better for you, but that still challenges you some. Without me being in your living room with you I cannot know what is working for you and what is not so you need to adapt whenever necessary. If you do a workout that is too challenging or too easy for you the first time, then the next time you come back to do it, simply slow down if it was too fast, lift heavier weights if the lighter weights didn’t challenge you enough, etc.