Check the Gross Trailer Weight (that's the trailer + the load) against the manufacturer's stated Maximum Towing Capacity for your vehicle.
The 85% Rule
In addition to the manufacturer’s stated Max. Towing Capacity figures it is recommended that the weight to be towed should not exceed 85% of the "kerb weight" of the towing vehicle. The "kerb weight" is defined as the weight of the vehicle plus a full tank of petrol and 75kg.
The load must not project outside of the trailer as this can be very dangerous to other drivers and the stability of the trailer.
It’s dangerous and illegal for the load to stick out beyond the edges of the trailer.
Distribute weight evenly as much as possible. Overloading one side or having excess weight toward the nose or tail of the trailer can seriously impact the stability of trailers.
Most trailers will have a stated "Recommended Nose Weight" which should be followed.