Hmm... I drink water. Also water, and more water after that!
Kidding aside, I like herbal tea (hot or iced) with a few drops of stevia (sweetener packets have carbs!) I drink a cup of British blend tea in the morning with my 1 oz of skim milk. Once in a while I add some Mio or Crystal Light w/Splenda drops to my water, and a few times per week I will have flavored unsweetened seltzer. All of these are okayed by my coach.
As for my water, I just try to schedule it. Drink a glass in the morning, drink so many ounces between breakfast and lunch, drink another so many ounces between lunch and dinner. Gets it done!