ptimizing for images
The image you link to in your social data does not actually have to be on the page, but it should represent your content well. The image allows you to controll what people see when they share your content, so it's important to use quality images.
Every social platform has different standards for sizing. Typically, it's easier to keep it simple and choose one image size that will work for all services.
Twitter thumbnail: 120x120px Twitter large image: 280x150px Facebook: Standards vary, but an image at least 200x200px works best. Facebook recommends large images up to 1200px wide. In short, larger images offer you the most flexibility. When in doubt, test each page using the appropriate tool below to see exactly how your images will appear in snippits.
The importance of Open Graph data
If you could choose only one type of meta data to include, your best bet is Open Graph. That's because all the platforms can use it as a fallback, including Twitter to a large degree.
Facebook page insights
The meta property "fb:admins" requires that you enter your numeric Facebook id number, and gives you access to analytics about how your website content is shared on Facebook. Read more about Page Insights, including how to set it up and discover your numeric id.