I always work in Document mode and think that this way, the worksheet is more clear than a succession of lines of commands.
As to enter a fraction, the simplest way is to write first the two round bracket (), then press once on the left arrow. You are between the two bracket and can start to write your expression.
Of course, il would be a plus if they were a shortcut on the keyboard. Moreover, in the "Fenced" palette, you have to click on the left bracket, write your expression and then click on the right bracket. My suggestion is that it should be set up in a way that when you click a bracket, the pair is automatically insert in the worksheet. Then press once on the left arrow and voila!
For a new user, we should help him to do things in Document mode since this is the path that Maple decided to pursue since Maple 9. I admit that it is not perfect yet, for example, I am stunt ot see that the following still produce an error in Maple 13 in Document mode (but not in worksheet mode):
f:=x -> if x=0 then 0 else 1 end if:
Erro, invalid arrow procedure
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