First of congrats! I remember my first time many moons ago and its always a special memory!!!
As far as crowds, couple years ago opening weekend would be best time to go!!! Now as the event has progressed with greater ips and greater crowds opening night has not been like it once was... Now thats not to say that it will be super crowded or "biblical" like
@hatetofly says, like it is in October.
So with that your #1 tip is stay and scream.. Get to the parks early before they close and get into a stay and scream area. My fav and tradition is finnegans, but it might also have to do with they have Guiness on tap!!! But from what i head diagon alley was a pretty good one last year sense it let you into Halloween early last year... You choice will basically be on what house in the area of the park you want to do first!!!
#2 Express.... I think everybody on here will tell you know that express is your best friend if you can afford it!! Especially if your only going one night! Years ago id say dont worry about it especially sense i did not use it... I would just drink my way through the lines...but as the years have gotten busier and busier.... the three hour waits are just not for me!!! Thats not to mean you will see any three hour waits!!! maybe 1.5 maybe pushing 2 on the more popular houses...But i still rather not wait in line that long anymore and actually enjoy the event more outside of a queue line!! Listen to the guys podcast at
Orlando United Radio - Episode 39: The Choice is Yours « Orlando United they did a great job answering questions and some of them are HHN related!!!
#3 The back of the park will usually be less crowded at opening!!! so my plan of attack usually (always changes depending on the houses) is stay and scream at finnegans, do the two houses they have open in the sound stages, book it through hollywood and as park opens make it into kidzone... Hit the parade house first!!!! This is IMPORTANT as it lets back out into kidzone where you can then get into line for the tent house that right next to the entrance of the parade house...This will then let you out into MIB where you can then get into line for the house that is right there!!! So on a good night you can get 5-6 houses done within the first two hours (including early stay and scream)
#4. Have an awesome time!! This is my favorite time of the year and a pastime i have been doing for more than 10 years and each and every year i have an awesome time!!! The atmosphere is great and so much detail to see!! so make sure you take the time to look at EVERYTHING...Side note: if you like behind the scenes stuff....there is VIP tour they do during the day called Unmasking the Horror which takes you into the houses with lights on where your free to look at the amazing detail and take photos!!! really awesome stuff!!!! Here are some of my photos I took during HHN 23
http://s1297.photobucket.com/user/Rschwahl/slideshow/HHN Unmasking the Horror