There are many great choices for the first real customization to make to a stock Emacs configuration, but I've chosen one that to me most represents taking the safety off: simplifying confirmations via yes-or-no-p. Lisp has a tradition of using the p-suffix to denote predicates, statements which can be either true or false. Emacs offers excellent built-in help facilities, one of which searches the documentation of symbols (i.e., docstrings) for a pattern. Using this help facility, called apropos-documentation (C-h d yes-or-no-p), describes the function of interest as:

(yes-or-no-p PROMPT)

Ask user a yes-or-no question. Return t if answer is yes, and nil if the answer is no. PROMPT is the string to display to ask the question. It should end in a space; `yes-or-no-p' adds "(yes or no) " to it.

The user must confirm the answer with RET, and can edit it until it has been confirmed.

Typing yes and no quickly becomes tiresome. Thankfully there's y-or-n-p, described as:

(y-or-n-p PROMPT)

Ask user a "y or n" question. Return t if answer is "y". PROMPT is the string to display to ask the question. It should end in a space; `y-or-n-p' adds "(y or n) " to it.

No confirmation of the answer is requested; a single character is enough. SPC also means yes, and DEL means no.

This feels dangerous, but Emacs has great undo capabilities and the convenience is appreciable, so let's pull the trigger. 

(fset 'yes-or-no-p 'y-or-n-p)

The reason that I've used fset above is that symbols have separate function and value cells, similar to how Lisp uses address (car) and data (cdr) cells.