Lots of great info, tips and advice already posted for the OP question. When I first started pulling a cargo trailer, I also looked here for tips and advice. I did weigh both tires and tongue with bathroom scales, did the math, moved things around, weighed again looking for that 10-15% tongue weight. I believe that is a great exercise to give you an ideal of the "Ideal" weight distribution. but not practical on a long distance trip. The act of loading/unloading, clothes distribution from a clean/dirty baggage separation, adding newly purchased items while on a trip, the weight of an ice chest changing nearly every stop, combinations are endless. You definitely want more weight in front of the axle, the U-haul video already posted shows a great example of what happens when you have a heavily loaded rear trailer. DON'T DO THIS!
You want a tightly packed trailer (not overloaded) to prevent weight from shifting to the back giving the undesirable heavy rear loading. If you experience the trailer wagging, slow down and pull over as soon as possible and re-distribute weight to the front. Keep in mind, the more weight you tow, the more your stopping distance increases. Deter from heavy breaking while leaned over in a corner, the trailer weight could push your rear wheel into a skid.
Enjoy your trailer, it's a great accessory!!!