Writing topic sentences at the start of each paragraph helps your reader get to the crux of your message immediately. The topic sentences in your essay contain the key information with every other sentence explaining or adding to the topic sentence. If a sentence does not develop from the topic sentence, you should move it or cut it out.
Think of your topic sentences as the headline to each paragraph, announcing the new point you want to make.
When it comes to new products, few businesses are more perilous than making civil aircraft. Aircraft can cost millions to develop. Boeing gambled the company when it launched the 747, spending $2 billion on the project, 2.5 times the value of the firm. Twice as big and efficient as anything else in the air, the jumbo has earned the Seattle company $20 billion in profit since they first flew, 30 years ago almost to the day.
By writing the main point in the first sentence, your reader quickly gets the message. The supporting facts and views follow logically from the first topic sentence.