Images can make or break a website. The quality of the images, especially the hero shots on the home page and other important pages are critial.
When choosing website images there are a few things to watch out for.
Image size
Images should generally be between 1200 and 2400 pixels wide, and well under 1 megabyte or MB (1000 kilobytes or KB) or they may slow your page’s loading time.
Use an image editor to resample (reduce the pixel size) and compress the image.
Framing
It is important to consider that the image needs to be able to be cropped and shown in different viewports of a responsive design (like a smartphone, widescreen etc).
Consider how your photo will look in different scales and cropping.
Copyright
Photos may have publishing rights associated with them and you may get into trouble if you just copy-and-paste from the web without checking the usage rights.
You can always pay for good stock photos from places like Shutterstock or iStock, or do an advanced image search in Google for the appropriate usage rights.