I would suggest getting some of those butterfly bandages (I think that's the name, the tiny ones that have 2 adhesive ends and one thin inner section) and putting them on to hold it together (which is what they are for) then throw some neosporin on and put a larger bandage over the entire thing. This will reduce the size of the scar and stop it from fanning up or worming (as I like to call it when you have a deep enough cut that ends up with all the small lines on it like the segments on a worm).

But yeah, butterfly bandages, neosporin, and a larger bandage, this should turn any scar into a pencil thin line.