You can use concrete because it is easy to work with but to make it attractive you will have to tint or paint it. Another important thing to do is assemble all of the proper tools ahead of time. What tools you will need will depend on the type of fireplace you are building, including the shape and size. For a large fireplace you may need to rent a small excavator or power tamp while a small one may only require a pickaxe or shovel. If you have decided to use brick and lay it yourself you will need the equipment that is necessary for bricklaying. If you decide on concrete you will need a cement mixer and a trowel.
The next thing to consider is how you are going to power the fireplace. If you have decided to use gas you will have to have a professional to run a gas line from the fireplace to your home. This has to be done safely and correctly to help ensure the reliability of the outdoor fireplace and to make sure there is no gas leak that could cause it to explode or catch fire. If you are going to use a wood fire then you will need to dig a pit so the fire will be beneath the surface of the fireplace area and enclosed to help prevent spreading the fire and stray sparks. If you are unsure if you can complete the project call a professional to do it.