How much to should i take home for assignment fee?

[Marquell Jones]

since I am building capital, I am fining properties for investors, (Birdogging), now my question is, how much money should I take for an assignment?  Should I see how much the seller is selling it for and then take the difference of buyer (investor) price? Help me understand because I feel as though I have a possible deal coming up.  Open to all ways to do this. And tell me why I would want to use these techniques.