We have made this really easy indeed, and it is extremely important.
There are several services which are free and efficient, including AddThis and ShareThis.
We use ShareThis.
On the administration dashboard there is a link to the Social Media settings:
and then you enter your various social media URLs, handles etc:
Additionally if you use either ShareThis or AddThis you can enter the code appropriate to your account
These items are automatically merged into every page for you.
You are also able to enter and maintain OG (Open Graph) tags - which are required by Facebook and Twitter,
Again from the dashboard simply select the Configuration link and you can enter the default images for Twitter and Facebook
Each page has the ability to add further descriptions and keywords which will be picked up by social media.
You select which (if any) of the social media services you wish to use in the page control via simply checkbox. The page's banner image is automatically used for the image in social media.
If you look at the bottom of this page you will see the AddThis bar and on the footer a link for Facebook and Twitter plus an email icon. We currently only use these two services, but if you use others their logos and link will appear automatically.