Honestly and I'm sure it's not the answer your friend wants, but the best bet these days is to use the money they'd spend on buying likes / shares to advertise instead. With multi-layered targeting in ads it's a lot easier to really hone down your target audience and if they're serving up great content it should convert well.
If it's pushing to an external site, I'd run an engagement campaign alongside a traffic one at the same time. The former will really help with social proof which should help the latter perform better.
And honestly, the page where there's fake likes (that i didn't arrange.. just randomly started one day and went to 3k likes) .... It was generating sales naturally.
Mixing it with ads, I guess helped naturalize it all but this same page now top FBs for the exact keywords
Just got an SMM panel to give a go on liking ads.. increase the look of engagement