It would certainly be useful to display such a guide, so I would like to do that.
However, I don't think using fmt.Print to output to standard output is a very good idea.
That said, the logger is currently customized, and there is no policy in place for how such messages should be displayed to users in the development of deck.

I used the logger initially.
But it does not print log unless --verbose.
And its format is JSON object, which is not the best human-readable format on terminal.

You are right. I have filed an issue for resolution under #393.

We should probably use (*cobra.Command).Print, but since we can't use it in the part you are changing, we need to think of a way to handle it properly in the upper layer.

I thought it would be better to use cmd.Print when deck.New, deck.Create, or deck.CreateFrom in ./cmd return an error.
This change will result in more than one line being modified, and instruction messages will be displayed even for errors other than client creation errors, but this approach is better because it is more loosely coupled.
You are welcome to make this change yourself, or I can do it for us.

It's done, right? It looks good, so I'll merge it. Thank you!