Your first sentence is the key to grabbing the attention of your reader and have them commit to your article and your idea. If you can draw the reader in with your first sentence, you can lead them into wanting to learn more.
If the Web page survives this first — extremely harsh — 10-second judgment, readers will look around a bit. However, they’re still highly likely to leave during the subsequent 20 seconds of their visit. Only after people have stayed on a page for about 30 seconds does the curve become relatively flat. People continue to leave every second, but at a much slower rate than during the first 30 seconds. – Jakob Nielsen
Therefore, it makes sense to spend the time necessary to hook your reader. You have very little time to attract and retain their attention and the first step is the opening sentence.
After you’ve hooked your reader, quickly develop your story or message. Your reader wants to find out more and it’s your job to give them what they want and simultaneously sell them your position, sell your product, or entertain them — whatever your goal may be.