A really simple way to scale your campaign is to relaunch it with a 'lookalike audience'.
If you've had success selling a particular design aimed at Civil Engineers, you would have selected a bunch of civil engineering related interests. FaceBook goes through all this data and gives you another set of audience with similar characteristics.
The actual data that FaceBook analyses to duplicate this audience is a bit of a mystery to me but it definitely works and I've been able to relaunch my campaign(s), sometimes with the same level of success that the initial launch had!
I'd recommend doing this with pretty much every successful campaign you have.
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