my biggest adversary and main focus lately in course/crit races - timing. I typically sprint a bit longer and fortunately am able to sustain a pretty strong speed even once I taper off but it's not ideal. Last night I felt much more confident, relaxed, and aware when we came down to the final sprint. I waited a bit longer than the protected sprinter, who jumped pretty early, and pulled him back in quite a bit by the finish - not being right on his wheel from the beginning didn't do me any favors though.
For example watch Guardini beat Cav in the Giro this year, Just jump a little early and hope for the best.
Stay on the sprinter's wheel during the lead out... just before you anticipate they will kick, you kick suddenly to the person's side that you think they will kick out to, thereby blocking them just a smidgeon during your kick. That slight pause in that other sprinter's kick will be enough to give you a gap on that sprinter while they momentarily restart their kick, person will be most likely unable to hop onto your wheel.... then proceed to your strengths. You'll need some luck, too.