You have met the intermediate standard for wall pushups, so next time do 3 sets, but stop the set if you start getting shaky. Take a long enough rest between sets that you feel strong for the next set. Be sure to keep a log and be patient, you will be stronger every week. Time spent on these early steps will pay dividends later. Keep us advised of your progress, there is plenty of support to be had on these forums.
Definitely add a 3rd set, and look to just add a rep or two each week. Pushing through shaking on Step 1 isn't likely a good idea (as Coach Wade points out).
As others have noted, it if you stick with it, and increase gradually, things will work out.
Also, as you get used to the moves, and if you lose weight in the meantime, things may speed up a bit for you over time.
The biggest trick is not to be in a rush!
>>The biggest trick is not to be in a rush!
I hear you. And this is exactly what really resonated with me when I read the book. I've yo yo'd up and down with strength training for some years. Always had to give up as it starts to effect my adversely. My hope is that CC can offer some rehabilitation for my somewhat abused body!