#1 Heavy fins yes, leg weights no. You will learn to do w/o the leg weights. In the meantime they get forgotten, get lost, and worst of all get left on when you hand over your BCD next to a zodiac.
#2 Be religious about not wearing anything larger than boxer/briefs (bras allowed for the women) that is not a moisture-wicking fabric. The chilling effects from a cotton t-shirt are amazing. I've had this battle with too many modest types (typically women, and young persons in general) that insisted on not getting properly undressed on-site, then time and again come out of the water with throughly needless chills beacuse they wore sweatpants, or a T-shirt, etc. under their proper undersuit. Save yourself the grief and be a believer from the start. By my experience hunting or even XC-ski underwear isn't as warm as merino wool products, and merino wool tends to dry fast and absorb very few odors (dive longjohns can be a stunningly powerful odor).
# 3 and bonus points
Become and remain religious about taking care of your suit's zipper too.
Before getting up from wherever you sit to fasten straps: check that air definetly goes into the suit (this catches a not-attached inflator hose and hopefully an open zipper too). Next check that air also exits the vent of the suit. Listen too to try and hear if the air hose is constantly bleeding in air. BTW some suits (mostly older ones) leak from the air-out vent whenever it is fully open.
Its really nice to have an undersuit that is a little loose, one that will never restrict your movements even if you add a few pounds. You should be able to do a few deep squats with no danger of stressing the seams. I read that you dive a BCD and single tank, but nonetheless check if you could reach to open doubles valves, even close the isolator (center) valve while wearing your undersuit and suit. I've also learned that a super fluffy Weezle looks like the Michelin man but crunches down more completely and more softly than blanket-like undersuits: a blanket-like suit can bind painfully at the elbows and knees.
Everyone thinks their their new dry glove system is the best in the world when they just switched to it, equally many hate the same system once they are tired of its faults. They all have plusses and minuses. Carry extra glove liners. I usually carry 3-finger 8mm wetmitts as another backup.
If you have a dryglove hole that threatens to end your dive before it starts, if there are no better solutions avilable, sometimes you get great milage out of duct tape.
People can get very upset about how you should always use the suit or (more commonly) never use the suit for bouyancy. Someday it might be nice to be fully capable of using either one; I've had one inflator hose go problematic (usually constantly, very slightly inflating) on maybe 1-2 % of my dives, not so bad if you are also OK with just the suit.
As a female I'm distinctly less thrilled abou a pee valve. Nature's call is vastly less when you are both warm and dry. If it's a slight problem a small bag of chips before a dive can keep your blood volume up while still reducing the need to go. A tip I learned from Scubaboard!