If you are looking to lose weight healthily, so it stays off for longer, then gradual loss is best, 1-2 pounds per week is the norm.
The best time to weigh yourself is first thing in the morning, after emptying your bladder. This is when your weight will be most accurate. If you weigh yourself later in the day, you will probably be a few pounds heavier, as your body will have taken on water throughout that day.
Rather than weigh yourself daily, try to only do it once per week, weight will also fluctuate during your menstrual cycle. I always think it's better to judge weight loss by inch loss, measure yourself, (waist, upper thigh, bust, hips and upper arm) once per month and judge how you feel and look in your clothing. Unfortunately, far too many people place too much emphasis on what they weigh on the scales.