I agree with Cgarch excellent post. I have a trailer and would add a few things. My 11 Commandments
1. Keep weight as low as you can. Do not have weight up high. (Like a couple of gallons of water.)
2. Respect weight limits. I would keep it lower than max weight.
3. Carry extra parts for the trailer especially trailer hitch pins, axle nuts, and skewers. (Don't forget the extra 16" tubes)
4. Pick up a Hebie or Pletscher dual kickstand. Put rubber tips on the ends (carry extras) Trailers do not stand up well when parked.
5. Big Water Proof Bag that fits your trailer. (Buy the one that is specific for your trailer)
6. A good net attachment system over the bag.
7. Proper tools to change a rear flat & practice changing 1 (U will replace your quick release skewers with a skewer, hitch pin & bolt)
8. I like front panniers to add a little balance and to get to things I need quickly. (Also means you don't over pack the trailer bag)
9. Pack items in different colored dry bags to easily identify items (Easier in the pouring rain and when dark)
10. If possible, practice riding your bike with full gear/trailer on the straight, climbing, & most of all on long twisty downhill descents.
(This way you will get use to handling of your bike and trailer (It will help you fine tune your weight and balance)
11. Finally check the bolts, hitch pins, trailer, wheels and tires daily. One can never be too safe. Good luck with your trip.-Bob