If you’re like me, you were taught to hit the spacebar twice at the end of a sentence on those clumsy old manual typewriters in your high school typing class.
That was a lifetime ago, and language and punctuation trends have evolved. Those double spaces after periods, question marks and exclamation marks make a writer look like an amateur; you will look infinitely more professional by inserting a single space after end punctuation marks.
Another tip on becoming a better writer
Become a better reader. Whether you are reading for pure enjoyment or to become informed, the intangible benefits are that you will increase your vocabulary and gain a better understanding of sentence structure.
This is not a goal unto itself—you will rarely be called upon to discuss sentence structure, after all—but as you read, you will be more aware of the role of punctuation. It helps introduce an idea and give us cues about what comes next. Punctuation is critical to transmitting the author’s ideas. It’s a wonderful tool–let it work for you!