Take advantage of the 'View on Instagram' link on Facebook.
This trick works well especially if you already have a good following.
Either way, here's the secret sauce: Don't flood your feed! Only share you best Instagram pictures on Facebook.
Don't share every single picture, you'll pollute your friends feed and it will just be annoying. Instead, share only the best ones. That way, they will stand out of the crowd and will usually get a better response.
Then let the magic do its thing: your friend will see your Instagram pictures in their feed every now and then increasing your chance to have them follow you.