If you’re writing your own material, it’s often very hard to see the mistakes because you’re too close to the project. That’s why you must get someone else to read it over for you. Preferably someone who is not afraid to point out all of the errors, no matter how small they may be.
This person will help you to see the errors that you would have otherwise missed, and they can also offer constructive criticism on how to improve your work.
It’s important to find someone whose opinion you trust, and who will give you honest feedback.
Irrespective of the tight deadlines you may have – you must never, ever launch a marketing campaign (no matter how small) until you’ve checked and double checked for mistakes.
Having someone else read your work is an essential part of the editing process, so don’t skip this step!