I agree with all of this except for the advice to delay using your non-dominant hand. I did and would advise using it from day 1. Just do WTG on the cheeks using left hand for the left cheek and right hand for the right cheek and then put it away. I am right-handed and was very afraid of using the left hand, but within a month or a month-and-a-half I found I actually shaved BETTER with my non-dominant hand. I'm now over 250 straight razor shaves and I still think my non-dominant hand is a slightly better shaver.Sometime folks think that they need to do a full three pass shave on their first attempt using a straight razor. That is a guarantee of discouragement. Placing a naked blade against your throat or upper lip the first time can be intimidating and you are bound to be nervous.
I suggest that the first time you use a straight that you should use only your dominant hand and you should shave only the cheek on that side using a single with the grain pass. Then complete the remainder of your shave with DE razor or even a cartridge razor if that is what you have.
The next day, try to shave both cheeks WTG using your dominant hand.
The following day, try shaving your entire face WTG except the chin and mustache area that pose the greatest difficulty for many people.
Then try shaving your entire face WTG.
Once you are comfortable shaving WTG, the start trying XTG and ATG passes.
Finally, once you are comfortable shaving all passes with your dominant hand, try to learn how to use your opposite hand. I you have any degree of ambidextrous skills, using both hands can make shaving some parts of your face easier. However, some folks never learn to use their off hand. So, if you have difficulty learning, stick with your dominant hand. When shaving top to bottom, I use the hand on the same side of my face, but when shaving in other directions, I find it is easier to use the opposite hand. Do whatever seems most natural for you.
My theory is that since I had never used it before for any shaving whatsoever, I had no bad habits to undo. My left hand learned to shave with a straight razor and that was its first experience. So now it is really good at shaving with a straight razor. (My right hand, on the other hand [pun intended], learned to shave with a cartridge razor, and then with a DE, and then with an SE, and then with a straight razor, so it had some habits that didn't work perfectly and it had to "re-learn" to shave.)
Just my opinion and experience.