When making marketing material it’s likely that you are going to want to use images on the material to support the information that you are providing, however it’s important to think about where those images are coming from as they could be protected under copyright law.
Most images that you search for online are copyrighted this means that you are not allowed to use these images unless you have the permission of the legal owner of the image.
You can actually purchase the rights to some images online for a fairly low cost however it may be easier and cheaper to instead you your own photographs or have a photographer produce images for you and sell you the rights to the images. This way the images that you pay for will be exactly what you want without compromise.
Ensure that if you do use your own images that you place a copyright on them so that other can’t use your images without your permission.