Stop MS Word from selecting more than I want

Under File/Options/Advanced, there is the option 'When selecting, automatically select entire word'. It is on by default, you can switch it off.

You shouldn't need to move your cursor right back to where you started, just back up a little....specifically to anywhere within the word that you initially started your selection from.

If the snippet you want to select does not extend into the next line, you can also use block selection with Alt+Drag.