This is my easy guide to leaving messages with a shortcut so that you do not have to keep typing in the same thing over and over again or use the slow "copy and paste" method.
First of all go into your Settings and go to General > Keyboard
Scroll to the bottom and you will see the Shortcuts section. If you do not have this option it is because your iOS is too old.
Add your shortcuts. If you don't already have the emoticon pictures then go into the International keyboards just above the Shortcuts and select Emoji.
Something short like a letter plus a number works best. When you visit someone's wall you can now quickly add a message that you commonly use. Just type the shortcut and Autocorrect will do the rest!