Waking up to wrong fluids can affect the rate of hydration in the body. Anyways, you are dehydrated at night with your body going though a lot of repairs and not only is your body not getting any food, but also water. So drinking coffee, tea can further dehydrate you.
300ml-500ml of water in the morning is great to ward off dehydration. If you find it queasy to drink plain water, you can add lemon to it. This will give you your quota of Vitamin C too.
Drinking water half hour before your main meals is great as it helps to absorb all the water-soluble vitamins such as all B group vitamins, Vitamin C which will be absorbed better from the food.
Add another 500 ml of water if you are exercising.
Last but not the least, Keep sipping water through out the day. This will keep you hydrated and refreshed.