What is a blown highlight? I can assure you it's not a bad haircut from the local salon.
Its when the camera's sensor can't cope with the amount of light hitting it. Certain areas of the image won't retain any detail so you won't be able to recover the information in post-processing.
You can check this by reviewing your histogram, from the previous tip anything pushed up to the right could mean your highlights are blown.
Don't worry, there are a few simple methods you can do to overcome this.
1. Purposufully underexpose your image by exposure compensation
2. Use the cameras bracketing function
Do let me know if there are specific topics that you would like to cover in future tips or posts.