Kawasaki Ninja 250R Wont Start or Turn On

Is your Kawasaki ninja 250r wont start or it's hard to turn on? don't worry, it's not a big problem, it's usually because a cold engine. So.. how to solve this problem? Well guys.. I'm not an expert riders and not knowing lots about how to solve motorcycles problem but sometime, I also try to find how to maintenance bikes by self. There's lot of factor that can make your ninja 250r wont to turn