I'm writing this list as I sit here. I'm sure I've left out something but it's a start for someone.
1. Load heavy items in the center of the trailer.
2. Keep heavy items low in the trailer
3. Load
light, fluff items at the ends of the trailer.
4. Load only
light items on the rear bumper.
5. Keep big loose items out of the trailer.
6. Keep trailer tire pressures at maximum rating, typically 50 lbs.
7. Carry a small compressor and check tire pressure regularly.
8. We have pressure and temperature sensors on our
tires. Ginny monitors them in the tow vehicle.
9. Increase the tow vehicle's tire pressure to increase sidewall stiffness. In our Honds CRV it was 39 rear and 34 front compared to the normal 26.
10. Mounted Camera in rear window of trailer, monitor in Tow vehicle, Also we carry extended mirrors.
11. Know trailer
weight, we weigh at the town's transfer station before we leave every year.
12 Know tongue weight. We use the bathroom scale and a bottle jack and measure a couple of times a year.
13. We travel a lot and replace 2 of our Goodyear Marathons every 3 years. (We are off the beaten path a lot.)
14. Check
lights before starting every day.
15. Have partner check all mechanical connections.
16. Use a key lock on ball locking mechanism.
17. Use a locking device on ball mount (not a pin and clip).
18. Use a stiffing member to keep ball mount from wiggling in receiver.
19. Regularly check ball in ball support, check hitch mounting bolts.
20. Shove ball support as far as it will go in the hitch receiver and drill a new hole to get ball as close to tow vehicle
axle as possible.
21. Each morning when you're leaving your campsite, activate the brake controllers manual switch. Practice in case of a sway emergency and to test your trailer
brakes.
22. Add a break-away switch to your trailer.
23. In the tow vehicle we try to put heavy items over or in front of the rear
axle.
24. Add an anti-sway bar, inexpensive insurance.
I'm sure there's more but the Shrimp Scampi is ready...