Terms of Endearment
One of the easiest ways to flirt over text is to use terms that will indirectly convey the other person that you are interested. Send a simple message, which says "hello baby" and if you get a reply, you have one foot in the door. There are a plethora of terms that you could use, like honey, bunny, sweets, cupcake, sugar, etc.; just try to use the one that a person can identify with.