The only advice I have may depend upon the type of prep you're doing. For my prep, I also had to not eat solid foods, but was allowed broth, jello, etc. Then I had to mix a powder into 64 oz. of a drink (Gatorade) and drink it over a short period of time.
The drink didn't taste bad at all, even though I'm not a fan of Gatorade. However, because I had been eating broth and jello, I found it very hard to drink the 64 oz. It's hard to drink 64oz of something when you're not thirsty. If I had to do it again, I would refrain from consuming the broth and jello for a period of time before having to take the 64 oz. mixture.