First and foremost-you MUST add lemon! Not only is it delish but so good for you. Lemon juice cleanses your system, is great for your skin and super high in vitamin c. If you don't like lemon I encourage you to give it a try, your skin and body will thank you.
Second-go crazy! Add whatever fruit you like! I often add berries, oranges and sometimes ginger for a little zing.
Third-just remember to clean out/switch your filter and change the fruit regularly. Bacteria and molds can form which of course isn't good for anyone.