It's been my experience that I need to get plenty of sleep, about 8 hours. What makes the difference for me is that if I'm tired, I start getting bad cravings for simple carbs. And in my case, simple carbs are bad. They stir up my hunger and cravings.
I don't actually count calories, but keep a deficit due to being vigilant about my portion sizes and tracking what I eat (I keep a food journal). I've found that I have a much easier time sticking to plan and losing if I avoid simple carbs. Once again, they stir up my hunger and cravings. When I eat healthy fats, proteins, and complex carbs, I'm more satisfied and am less likely to overeat.
Drinking a certain amount of water doesn't seem to make a difference for me, neither does the number of meals I have nor when I eat them.
Hope this helps!