Start killing more. Over time you'll become use to it. Most people start with small animals and build up. If you become confident move to killing men (you'd think women would come before men but people don't care as much when you kill men so it's easier to hide it) then when you get good you kill the women and maybe even children. That's when the cops really get involved. Want to get real ballsy? Start leaving the police riddles and shit. Find the one leading the investigation on your case. Write that person personal letters. Go nuts and send them fingers or write the letters using blood or something. Kidnap their partner, then maybe their spouse or kid and off them to. Flee and move to another state and leave everyone wondering who you were. You'll probably even gets cool serial killer name but if you want that I recommend going for some sort of theme with your murders. If you get through this then you should be pretty okay around gore and then you can go watch horror movies or go to med school or whatever you wanted to do originally.