Hi guys, I'm a newbie at wearing hair and I'm interested in dying my hair, both system and normal. I'm just curious has anyone any tips?

I do have a couple of questions
1) Are you supposed to only dye your hair from light to dark or can you go from dark to light?
2) If you leave the hair dye in for say, 1/3 of the time in your hair, would that give you a good results?
3) Finally can anyone recommend a good hair dye?