Sans context, let's try a possible scenario.[...]
Make your recommendations with the campaign's success at the forefront--not just your bottom line.
In America "the bottom line" always means profit.I believe it's short for "...at the forefront of your mind".
"The bottom line" = the minimum you will accept.
So the sentence means: The author is telling [John] to write some recommendations that will lead to the campaign doing really well, not just OK.