Here is my planning:
If you need to fly:
Go to http://flights.google.com and search for the dates you want.
Add a watch on that search.
You will get e-mailed for any price changes on it. I got a $500 flight for $275 due to having this.
It will also give you an idea about volatility (if any). If it keeps changing, then it may go lower. If it never changes, it might not drop.
Always book directly through the airline (unless you need expedia points or save on your hotel due to it), as they will help you more as a direct booking.
For hotel: Start at Expedia/Trivago. Make sure you set your search terms for refundable (it will be more expensive) and remember the 17% hotel tax. (I think that's the right rate). This will give you a ballpark figure. You can book, then cancel later. Personally, I use this as a guide, then check the hotel site directly, just in case they have any special deals. Unless I save a ton, I'll use Expedia.
Enter into the housing lottery for gencon. housing block is cheaper overall, but harder to get a downtown room. If you get one downtown (and want it there), great! book it. then cancel your existing hotel booking. If you don't care, then it is easy to get a non-downtown hotel, often cheaper than a direct booking. Again, cancel your direct booking afterwards.
Parking! If you are driving, make sure you have parking, whether it is at your hotel, or if you are driving in each day (whether local or airport), you pre-book at something like Gate 10 when they open it for pre-bookings.