Funny how we're all different. I tried a Camelback, but hated having anything on my back.
Here are the big ones I learned:
1. How you position yourself on your bike will change over time. Don't be afraid to constantly tweak your fit.
2. I had been having a lot of trouble with wanting to pull back my hands/arms, had three fittings, and still couldn't figure it out (shortened my stem, moved my saddle, etc.). After a year of riding, I finally figured out that my 40 handlebars were too wide. i switched to 38s and my hands fell naturally where they should have been the whole time. I'd been pulling back to compensate for too much width. Doh.
3. If you lose weight, buy new shorts asap. I, more than once, got my chamois caught on the nose of my saddle when remounting after a stop, or standing to pedal because my shorts were a tad loose. Tight shorts are safe shorts 
4. Don't be afraid to try men's gloves. My hands/fingers swell in the heat on long rides. I finally switched to a men's medium glove and am happy, and tried five not cheap women's gloves before I figured that one out.
5. My fav thing I learned to bring in my jersey on long rides: an old, thin washcloth in a ziplock. I don't know how many times I've used it to wipe my face in the Florida heat, and especially before reapplying sunscreen. Also, bring those wet wipes in the little packets. Great for the face and for hands after changing a tire.
2013 Kirk Frameworks JK Special/Selle Anatomica
2012 Gunnar Sport/Brooks B17
2001 Calfee Tetra Pro/Selle Anatomica
1984 Raleigh Sport/Brooks B66