Probably will need to remember to bring this back up about the time GR begins, but I've been thinking about this lately so I'll start it now. Of course, different users will have different issues so hopefully we'll get observations from others too.
For me, my most recent keyboard was the Apple wireless. So the keys were horizontal all the way across. I think all my other keyboards were as well. So this was an immediate issue for me, especially for my pinkies. I'd tend to fall short. This was always strange to me because even with the TB angle, the keys are an easier reach. Nevertheless, it was a problem for me.
I tried putting something between the top of the key blades to reduce the angle and that did help, but I didn't like having to take that extra step. Finally I figured out that my main problem was I had always held my elbows right against my side. If I moved my elbows outward so my arms came in at about a 45 degree angle to the space blade, I did much better. Since I type on my lap, I found I could just put my elbows on the low armrest of my chair and I'd be about perfect.
Short version, if you find yourself missing pinky keys a lot, try moving your elbows outward from your body more.
A big issue for many was hitting Enter when they wanted the apostrophe. In most cases I think all of us feel it is best to not change boundaries at first. Give yourself time to do the adjusting and then use boundaries to help with keys that just keep giving you a problem. But you might want to make an exception for the apostrophe/Enter boundary simply because of all the places where hitting Enter by mistake sends a message!
You could, of course, type messages in a text editor or word processor and then copy/paste on a message board, but if you aren't going to practice that way and you find that Enter key causing problems, just go ahead and change the apostrophe/Enter boundary (move slider closer to the apostrophe to emphasize it over "Enter". Later, as you adjust, you can always move it back.
Or do what some others do and remove Enter from the main layer so you have to hit Enter on the Green layer (pressing spacebar and Enter key). That way you can't accidentally hit it when trying for the apostrophe.
In my case, I had a similar problem with P/Backspace so I went ahead and changed that one to emphasize the P key. All the rest I waited awhile to see how well I adjusted to the defaults.
Unless you are already really good on a regular keyboard at touch typing numbers and symbols, I simply wouldn't focus on practicing with numbers and those symbols at first. After all, if you aren't good at them, you are probably having to look down at them anyway. So continue to treat those as special cases while you focus on letters and basic punctuation - which, for most people, will constitute most of what you do in real life. Which is why I like:
A common word 60 second test that will list all the words you missed at end AND how you typed them. Now, if you don't already type letters and basic punctuation fairly well, probably lots of typing tutors may be good or better than this so you develop touch typing from scratch. But if you already are decent, this is good, because:
You may well find certain specific words or letters you miss. I'd take the words listed at the end of a test and enter them into some kind of text editor and then, below a paragraph of these random words, type them over and over so I was really focusing on those I had problems with. As I do more tests at the site, I add more words to my practice list. In short order I would start noticing which letters gave me trouble so I would create practice material that included them a lot, even if they didn't appear on my online test.
Other times specific words gave me trouble because of the order of the characters. A good example was "like". This was because, on my dvorak layout, my left index finger would reach over to the right for the qwerty "G" key and then immediately have to come back and down for the K (that's V on qwerty). I just kept misjudging it, so I practiced such words a lot.
Eventually I had either adjusted well (only took me 10 days to get to my speed on a regular keyboard) or I had a short list of prime candidates for boundary changes. By this time, it was fine to start changing them, though I wouldn't do them all at once. Usually just one and see how it worked out, then add another.
Over time, sometimes I put a boundary back to default if I saw the situation reversing, but that is a gradual process.
A small, but important, step is something I teach beginning band students. Every time they pick up your flute, clarinet, sax, whatever, they should put ALL their fingers down on the right keys and only after that, lift up the ones you don't need for the first note. This way, every single time they pick up their instrument, they are also practicing the right position of the fingers. Well, same for the TextBlade. Best, whenever you are about ready to start typing again (any time you stop for 5 or more seconds), put those fingers on the home keys (there are little "wells" you can feel - or just look). Better to be too careful than start off sloppy.
If you are one of those who needed to adjust their elbows, this is also the time to make sure you have already made that adjustment.
It all may sound complicated. But you will probably adjust whether you do any of these things or not. But I think these may well speed up the process.