We were just there for the first time last weekend, and a great piece of advice I picked up here - I think maybe from macraven? - was to wear dry-fit type clothing, especially if it's going to be hot outside and/or you plan on doing the water rides. I found dry fit shirts and underwear on sale at
Walmart (Target has ok prices too but their women's dry fit short sleeve shirts right now have a very funky fit/cut to them), and took a couple pairs of running shorts as well as 2 pairs of swim/board shorts that I already had. I dried out pretty quickly after Jurassic Park and Ripsaw Falls (I came out looking like a wet rat on both of those rides, so I don't know how anyone could ride either one and not get fairly soaked), but my husband's khaki shorts and regular cotton underwear were still damp a couple hours later (he listened to me on the dry fit shirts but he did not believe me that our butts might get wet on the water rides). I also found the fabric to be more comfortable during the hottest part of the day than a cotton tank or tee.
Like several others above have already posted, taking advantage of early entry is huge for cutting way back on wait times in the HP areas, so I would try to do those first, and then if you're staying onsite you can use the express pass on most of the other attractions later. For example, the first day we left RPR about 40 minutes before EE, had a 10 minute walk to the gates at IOA and I think they actually started letting people in around 10-15 minutes early. We had only a few minute wait for the headliners in Hogsmeade, and since Hogwarts Express usually starts running around 20-30 minutes before US opens, we were going to take that over to Diagon Alley around 8:30. Unfortunately they were having problems and did not know when it would be back up, so we left Hogsmeade about 15-20 minutes before US was scheduled to open. It took about 10 minutes of brisk walking to get to the US gates and they were already letting people in, but it was still not crowded at all in Diagon Alley and we only waited about 5-10 minutes for Gringotts. After that, since it was just the two of us, we did the single rider line on Gringotts and were able to basically walk right on several times each day, even in mid-afternoon when the wait times were at their peak.
The lines for Ollivander's are also much shorter in Diagon Alley than in Hogsmeade, so my husband and I ended up being the only two people in our group and we both had wands "choose" us (yes, we're big nerds!). And, since Harry actually got his wand in Diagon Alley and not in Hogsmeade, you're technically being more accurate if you go to that Ollivander's
So that is another way to save time.
Also, if you are able to work it into your plans, I also read somewhere on these boards that the HP areas are very cool at night, so the first day we did all the HP stuff first thing, rode HE back over to IOA and did a few other rides there, took a break the first afternoon, came back around 5 and used express pass on things like Transformers and The Mummy (loved that ride!), ate dinner and then went back to Diagon Alley. It was not crowded at all and everything looked so neat after dark, especially the dragon. Some of the interactive wand stations are cooler at night too. We had breakfast at the Leaky Cauldron and lunch at both Leaky Cauldron and Three Broomsticks, and all three meals were great (Bumblebee Man's Taco Truck in the Simpsons area was also good).
Other than just having a rough plan for the HP stuff, we did not end up using a real touring plan at all for the trip. I definitely made some, but since the express pass made it so easy to just hop on a ride without having to schedule a fastpass window, we threw the plans out within the first hour and just did what sounded like the most fun at that moment. If you don't have the unlimited express pass, then you might have to do a bit more planning to minimize wait times, but if you have the pass, you really don't have to plan much at all.
They really did a fantastic job on all the HP areas, so even if you get stuck waiting in line for a bit, there are so many details to absorb and we had fun discussing various aspects of the books and movies that were sparked by seeing those little details. Have fun!
My hubby hates water rides bc he doesn't like walking around in wet unders afterwards. 
