Keep half of your beer free from additives. The best part about trying something new is learning what it adds, so you want to have a good baseline to compare against. I would also suggest only adding one new thing at a time to be able to pick out what that ingredient does.
I fully appreciate the excitement of adding things and experimenting, I usually try to do something different with 5 gallons of each of my 10 gallon brews. I'd highly recommend trying a batch with nothing different besides the yeast, and after tasting Jester King's Drink'in the sunbelt this weekend, I would recommend trying a hoppy wheat (I certainly will be soon.) They used Amarillo apparently, in addition to Falconer's Flight and Magnum, none of which have ever touched a wheat of mine before.