You actually need to get the aquarium ready before you get your goldfish home. You have to decide on the size of the tank as well as where you want to keep your aquarium. Where to set up the tank is an important point you must decide on. Apart from the angle of interior decoration, you need to keep in mind several very practical points:

Is there enough room in the aquarium?

Make sure there is because you will need to move around it while cleaning it. Don't put your aquarium up against a wall because you will need to check the back of the aquarium for the filtration. Don't put it on a shelf, as you would need to check the top of the aquarium for water changes and lighting. Your aquarium should be well ventilated to prevent it from getting overheating or developing mold.

Are there electrical sockets nearby?

You will need to have electrical outputs near the aquarium to run the filter and the air pump. Make sure that no loose cords are hanging dangerously around it. The wires should be out of view but the switches should be accessible. Make sure that you do not keep the aquarium near heat or AC vents, as they can overheat the tank.

Is your aquarium getting in the way?

You do not want to keep your Goldfish tank near a doorway or any place, where there is too much disturbance, as in people passing by, doors slamming shut, etc. That's because all these things might cause vibrations in the water levels and stress the goldfish out. They are overall placid things and need some peace and quiet. Also keep away the aquarium from direct as well as indirect sunlight as it may raise the room temperature and affect the water temperature, which means you must not place your aquarium near a window.

Is it in a place where you can change the water easily?

You will need to change the water in your aquarium once a month, so make sure you also have convenient access to a sink, and a faucet. Your aquarium might be too big to haul to the kitchen and you might end up sloshing water on the carpet and even hurting the goldfish.

Can whatever furniture you are putting in the aquarium withstand its weight?

An aquarium can get quite heavy once it is filled up with water. Make sure you put it on something that is strong and that the floor can take the weight too! Also make sure that the aquarium is stable and is not wobbling around dangerously. Consider buying an aquarium stand that would keep it level.